Refactors activities controller spec

Lots of specs here were really testing views, so those got moved into the view specs.
Move social links to partial
Script order matters
Tweaks the flow of sequence creation [#52539193]

Associating activities with a sequence is the most important part of creating them, but we can't do that association on the "new" page because the sequence doesn't yet exist on the server. This follows a pattern I used for page creation, creating an "empty" sequence with default values and redirecting to the edit view for that sequence rather than spending any time on the "new" view. 

https://www.pivotaltracker.com/story/show/52539193
Add font-awesome to gemfile.  Will use for snapshot icons.
Move the jQuery CDN links to head

I gave Sarah demo code for putting carousels in embeddables, but jQuery needs to be loaded already for those inline scripts to work.
Tweaks to view spec tests
Support for designating themes for activities or sequences

[#52741243] Adds the 'theme' field to the Sequence and LightweightActivities models, along with form fields to set or change it and tests to confirm those controls are present. The field is stored as a string, but we're using a select menu to pick from a fixed array of strings; that array is set as a constant in the initializer config/initializers/themes.rb .

https://www.pivotaltracker.com/story/show/52741243
Suppresses a warning in development
WIP on Theme object: 95% of this model
Finish themes testing
Fixes thème index listing
Using Theme objects instead of strings for Sequences and LightweightActivities

This is a slightly different implementation of [#52741243] to use the new Theme object instead of just a string.

https://www.pivotaltracker.com/story/show/52741243
Rename 'upstatement' layout to 'runtime'
First themes (HAS, MW) and CSS organization

[#52741509]

https://www.pivotaltracker.com/story/show/52741509
Oops - didn't define destroy
Move footer into new Project model

For [#52056969] and [#52741509] - the logo, URL and project title (and, logically, footer) should belong to a Project object, not the theme. This creates the Project and moves the right parts of Theme to that object.

https://www.pivotaltracker.com/story/show/52056969
Associate Sequences and Activities with a Project
Fixing up Projects controller
Fixing up Project admin