Merge pull request #5 from Hauptstimme/feature/api

Read-only JSON API
Revise tasks index UI
Celebrate the new user interface :saxophone:
Update title helper method
Filter out active users
Add specs for unauthorized context
Send emails about new comments
Merge pull request #7 from peccata/comments-mailing

Send emails about new comments
Remove turbolinks
Use Select2 for project participants
Restrict project write access to owner
Add tasks filter
Add colored priority badges
Add project links to dashboard
Merge pull request #8 from peccata/project-links

Add project links to dashboard
Clean up
Fix comment links
Update cache key for projects nav fragment
Select how many tasks per page
Merge pull request #9 from peccata/tasks-per-page

Select how many tasks per page