Implemented #738 Giving a user WRITE+ permissions on folder should not allow repo creation in root folder.
user can create repos only if he got explicitly permission for creating repos globally, or have WRITE+ permission on a group.
Then he can create repositories inside this group

pull request: update changeset list automatically - remove refresh icon

With most of the UI giving immediate response it was confusing that we had to
press 'refresh' manually'. The icon could also be misunderstood as a 'swap'
symbol or as reload/reset.

compare: show aggregated diff of what will be merged to other repo, using merge ancestor

pull_request.get_compare_data will also now return the ancestor that would be
used for actual merging. Showing a diff from that ancestor instead of the first
'new' changeset will give a more realistic diff that doesn't include merges.

compare: swap org and other when they refer to different repos, ie are pull request style

Pull requests will have a different from/to description - but in a consistent
and slightly better way that can be improved later.

A pull request diff is empathic: "How will this look for the peer I'm proposing to" style.

compare: rename optional compare_url parameter repo to other_repo

At the same time it is placed before other_ref_type and other_ref. Just to keep
a logical flow and (a new) consistency that will help the next refactoring.

Added missing migrations, and move update_repoinfo to RepoModel
migrations now update repo cache

repository extra fields implementation
- verion bump to 1.6
- migrations

Bring back rss icon for atom:
- http://www.mozilla.org/foundation/feed-icon-guidelines/
- http://en.wikipedia.org/wiki/Atom_%28standard%29

compare and diff: remove unused "bundle" functionality

The 'bundle' parameter was never set, incoming_changesets was thus always
False, remote_compare was thus always False, and InMemoryBundleRepo and
bundlerepo was neverused.

pull request: use unionrepo instead of outgoing

This makes it possible to look the 'moving target' symbols up in the right repo.

Using a revset with the right revisions also removes the need for pruning
changesets that are outside the requested range.

It will also not be confused by changesets that for some reason has been pulled
to the repo but haven't been merged yet. They are going to be 'merged' by the
'pull' request and should thus be a part of what is reviewed.

pull requeset: move stuff around, preparing for next change

- and make sure we don't pass unicode to Mercurial

header: don't use fixed position

A fixed div at the top prevents anchors and pageup/pagedown from working
correctly ... and it is not like the top menu items are used all the time -
next/previous page links would be more relevant to show in a fixed position.

made the upper menu as a dropdown to old fixed mode by clicking upper
semi transparent bar

make unread also a link, constantly was clicking that
- make the links and hover same as other links in that menu

don't show rss links - atom is the present and the future

- following the reasoning on http://selenic.com/pipermail/mercurial-devel/2012-December/046542.html

summary: show "Show by ID" toggler after the clone url

It looked like something important ... but most users don't need it.

summary: don't link explicitly to /summary

It is redundant and exposed ambiguous urls.

top menu: 'Repositories' is really also a 'Home' button

'Repositories' had a href="#" but it wasn't used - the sub menu is loaded and
shown when hovering.

The '/' front page is a more verbose view of repositories. It thus make sense
to let 'Repositories' point there.

git hook handler shouldn't ever use cache instances
- moved cache invalidation into finally block so we invalidate at latest possible stage
- added scm_instance_no_cache property to get non cached scm instances always

added recursion limit for stats gathering, sometimes it did >1000 loops which lead to python throwing max recursion depth exceeded error.
ref #642

css: set min-height on form fields

Necessary when pull request summary has no description and nothing expands the
div.

changeset comments: attempt to highlight the linked comment

This makes it slightly less confusing to follow a notification link to a page
with a lot of comments.

It is ugly, it seems like it doesn't work reliably, and the fixed top menu makes
target navigation unusable in general...

hide add repository button when you don't have at least write permission in group
ref #730

filter out repo groups choices to only ones that you have write+ access to. Before it was read+ access and you got proper
error saying that you don't have write permissions to group to create repo in. Filtering out the read groups is less confusing for users.
ref #730

Return a list of invlidated keys on mark_for_invalidation func
- log.debug list of invalidated keys