db: cleanup of repo group choices - better handling of root and better sorting groups_choices always get a groups list so there is no reason have code for creating a list. All the responsibility of creating the tuples is moved to _generate_choice - also for the magic top level entries. Also sort the choices by all path elements - not just the top level element.

syntax: glob
*.pyc
*.swp
*.sqlite
*.tox
*.egg-info
*.egg
*.mo
.eggs/
tarballcache/

syntax: regexp
^rcextensions
^build
^dist/
^docs/build/
^docs/_build/
^data$
^sql_dumps/
^\.settings$
^\.project$
^\.pydevproject$
^\.coverage$
^kallithea\.db$
^test\.db$
^Kallithea\.egg-info$
^my\.ini$
^fabfile.py
^\.idea$