Add spinner component
Upgrade react router
Make backbone mixin more robust

Do not replace the backbone model after a component has been unmounted
Add Spinner class to Spinner
Disable all model mutation methods on the client
Add spinner to TicketForm
Add spinner to TicketList
Fix ToggleStatusButton
Extract scrollToBottom function
Use Ticket#addHandler(...) in TicketView
Poor man's auto growing textarea
Add ElasticTextarea
Use html5 history api for routes
Enable multiline mode for comments
Do not add extra line breaks after saving a comment
Add linemode tooltip