Move exception_notifier into initializer
Constrain sequence IDs
Scope activities by readable
Adding and removing activities from sequences

[#51592849] Basic UX for the sequence <=> activity relationship.

https://www.pivotaltracker.com/story/show/51592849
Specs for adding/removing activities from sequences
Now I know how to do this (force an update error)
Make the sequence description text area WYSIWYG
Smooths out show page display
Quick cut at show styling for sequence page

For [#51592849], I'm reluctant to get too deep in the styling with a new skin coming, so this is just a rough cut.

https://www.pivotaltracker.com/story/show/51592849
WIP on refactoring reorderable lists into modules
WIP on styling edit page, reordering activities

[#51592849]

https://www.pivotaltracker.com/story/show/51592849
Un-pinning and updating a bunch of gems
Proper layout for activities in Sequence editing
Finishes Activity reordering within Sequences

[#51592849] This allows drag-and-drop reordering of activities within sequences, from the sequence edit page.

https://www.pivotaltracker.com/story/show/51592849
Notes on controller spec refactoring
New home page lists activities and sequences
Shouldn't have lost this CSS
Clear WIP JS for clarity