Imported some of the GPLv3'd changes from RhodeCode v2.2.5.

This imports changes between changesets 21af6c4eab3d and 6177597791c2 in
RhodeCode's original repository, including only changes to Python files and HTML.

RhodeCode clearly licensed its changes to these files under GPLv3
in their /LICENSE file, which states the following:
The Python code and integrated HTML are licensed under the GPLv3 license.

(See:
https://code.rhodecode.com/rhodecode/files/v2.2.5/LICENSE
or
http://web.archive.org/web/20140512193334/https://code.rhodecode.com/rhodecode/files/f3b123159901f15426d18e3dc395e8369f70ebe0/LICENSE
for an online copy of that LICENSE file)

Conservancy reviewed these changes and confirmed that they can be licensed as
a whole to the Kallithea project under GPLv3-only.

While some of the contents committed herein are clearly licensed
GPLv3-or-later, on the whole we must assume the are GPLv3-only, since the
statement above from RhodeCode indicates that they intend GPLv3-only as their
license, per GPLv3§14 and other relevant sections of GPLv3.

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

Implemented #379 defaults settings page for creation of repositories
- locking
- statistics, downloads
- repository type

Initial version of landing revisions ref #483
- fixed relevant tests for creation of repo
- added some tests for git

UI
- added clone-url into edit form on /settings page
- added help text into repo add/edit forms

#47 implemented Adding of new repo_groups+forms+validators. Fixed sorting of repo groups by main names in multiple locations. Removed some unneeded calls to self.sa for exchange to .query() methods.
Added new db unique key for Group

#109, added optional clone uri when creating repo.
Cleaned up repos controller moved common code into __load_data