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