Split core/models.py in core/models/*.py
Fetch commit files

cf #105
Be sure to reset token api remainging
code/diff/pr-comments templates are not reserved to PRs anymore

cf #105
Commits can now be displayed in a tab

cf #105
Little css tweaks
Better highlight of active file in diff tab
Make PR tabs scrollable if too much un line

Fixed #197
Conmits tabs can be closed

cf #105
Replace memoize (process) by our cached_method decorator (instance)
sdfsdf
Tabs are present on issues if a commit is displayed

cf #105
Make click on commit comments count open commit in tab

cf #105
Make prev/next comment work on diff with only one file

(done by always show the files list, even if only one files)

cf #105, but limited to commits (but there is more chances to have a
commit with one file, than for a PR)
Allow to create/edit/delete commit comments (in code, for now)

cf #105
Allow to create/edit/delete commit comments not in code

cf #105
Display comments count on commit tab

cf #105
Allow managing comments on commits not tied to the current issue/pr
Manage user infos on comments header
Count changed files on each commit