Prism Browse view

Adds a prism browse view to the controller; and a view for it
Browse Page Update
fixed browse page borders
flash message fix
New models and db schema for wayne to review.
Adds indices to some models.
Myprisms broken code for wayne to examine.
My Prisms Page

A very rudimentary my prisms page.

This needs an authorization system where you're only able to manage the things that the user 'owns'
Fixes (at least in theory) the highlight method according to the new models and eliminates unused code related to the sandbox.
fixed merge errors in header
NOW these should be the final models. Added a has_and_belongs_to_many relationship between facets and word_markings as well as a color attribute for facets.
Add CC licenses

Adds a rudementary license selector for new prisms
Updates old prisms to public domain
Adds license icon on prism#highlight and prism#visualize pages

references #195
Merge branch 'develop' of github.com:scholarslab/prism into develop

Conflicts:
	app/assets/stylesheets/media/_screen.scss
	app/controllers/prisms_controller.rb
	app/views/layouts/_header.html.erb
	app/views/pages/about.html.erb
	app/views/prisms/highlight.html.erb
	app/views/prisms/index.html.erb
Document titles should render HTML.
Merge branch 'develop' of github.com:scholarslab/prism into develop
Fixes tests

Updates tests to use 'Prism' object rather than the 'Document' object
Adds factories for a default Prism and one that is unlisted
Moves view specs for documents to prisms
Removes marking spec
Fixes #194. Makes SLab logo a better grey.

Puts SLab logo on its own line, below other footer content.
began work on new prism page
Moves link to Google web fonts inside head tag.

Consolidates references to web fonts into one link.
Removes unused div.