Add missing chosen-build dependency

To fix build
Use slug for preview
Add Taggle library for handling tags on the frontend

This is unstyled at the moment so shouldn't be merged into master
Remove default tags from hidden input and add split the tags by ,
install debugger for development env
refactor: extract main menu options into a helper
add tags option to admin main menu
Create Tag model.
move main menu rendering helpers to its own module. Refactor
add create action to TagsController. First approach
bundle + migrations
For the moment, Taggle needs to be instantiated right in the views using it
modify tags index view to enable tags creation and look up
the whole logic to look up tags starting by a given prefix
remove test controller
remove tags feature
rename some methods and better js
better condition to find db tags
lets be able to debug tests as well
wrap some sections of the admin tags view to easy testing