fixes #591 git backend was causing encoding errors when handling binary files
- added a test case for VCS lib tests

Fixed #585, checks for status of revision where to strict, and made opening pull request with those revision impossible due to previosly set status.
Checks now are made also for the repository.

#590 Add GET flag that controls the way the diff are generated, for pull requests we want to use non-bundle based diffs,
That are far better for doing code reviews. The /compare url still uses bundle compare for full comparision including the incoming changesets.
- Fixed tests

Add git version detection to warn users that Git used in system is to old. ref #588
- also show git version in system details in settings page

Make detecting bare Git repositories more robust

Git remote repositories may end on '.git', e.g. myrepo.git. Just checking
for a repository path to end on '.git' causes 'Repository not found' errors
in such a case. To distinguish between bare and normal Git repositories,
check if there is a '/.git' part at the end of the repository path
(i.e. if GIT_DIR is pointing to '.' (bare) or '.git').

#518 multiple issues patterns
- added logging
- some code cleanup
- added example of wiki pattern to .ini file
- updated contributors and changelog

Allowing multiple issue servers to be autolinked in the changeset view;
linking is now contingent on issue_server_link, issue_pat and issue_prefix
being defined; multiple servers can be used by specifying a common suffix on all
the above variables, ie ..

issue_server_link_1
issue_pat_1
issue_prefix_1

.. and ..

issue_server_link_other
issue_pat_other
issue_prefix_other

.. would be treated as two distinct servers, but ..

issue_pat_thing

.. would be ignored (since the other two requisite vars aren't present).

This patch is backwards compatible with existing variables (as a suffix
isn't needed).

fixed #570 explicit users group permissions can overwrite owner permissions
- added test for that case

swap the select values with revisions dynamically when switching the repos on pull request view
- fix the partial ajax request that should never do redirect

fixes #567 diff non-unicode encoding missmatch
- now uses safe_unicode ass all other parts of the system

fixes issues #566 non-ascii search params are crashing paginator
- those arguments needs to be converted to strings

Implemented patch from andrewsh ref #565 Add support for {netloc} and {scheme}
to alternative_gravatar_url

Implemented permissions for writing to repo
groups. Now only write access to group allows to create a repostiory
within that group

fixed issue #559 fixed bug in routing that mapped repo names with <name>_<num> in name as
if it was a request to url by repository ID

Permissions on group can be set in recursive mode setting defined permission to all children
- more explicit permissions
- fixes for empty values in permission form