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
Correctly link to the prisms browse page.
Removes merge conflict notes from prism css file.
Corrects (I think) the view for prism visualization.

There have been some contradictory commits since @bwalsh
committed at 6e437596c8c3662a693888f93f4ead2bb9885981. This commit reverts the
code back to that point, but adds the important semicolons to the javascript
code near the top, which @waynegraham added in 502fac2bba286be82352b0175c07297a665f9386.
Moves Prism CSS to an include.

Includes it in main application.css. Leaves it outside a particular media
query for now, since we may want the highlights printed out.
First pass at displaying highlighter colors on highlight page.
adding the myprisms page adds highlighter and eraser images
these were superfluous pages
Get tests functioning

Use self.primary_key syntax over set_primary_key (it's deprecated)
Removes tests for objects that do no exist
fixed merge errors in header
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.
Moves link to Google web fonts inside head tag.

Consolidates references to web fonts into one link.