Add option for importing a course from a named branch of a git repo
Only add mentoring application to INSTALLED_APPS when in virtualenv
Fixed bug of checking out the same branch multiple times and code review fixes
Translator comments and language fixes
Merge pull request #2283 from carsongee/cg/feature/git_branch_import

Add option for importing a course from a named branch of a git repo
Update import location of `prefer_xmodules`
Merge pull request #2848 from antoviaque/xblock-mentoring-optionalapp-fix

Only add mentoring application to INSTALLED_APPS when in virtualenv