Add spec file using before(:context) to reduce test time. With testing
almost identical things, unnecessary to make them completely atomic.
Includes two helper methods. Since the raw_content method is the only
function needed on that page, created the method in the spec instead
of adding another page object.

Setup new project/commit page object and update project/show to add
go_to_commit method. The go_to_commit method is near duplicate of
go_to_file method, but decided to split them off to reduce overall
refactoring and simplify language.

Also add selectors to commit box partial and update qa.rb to load
new page object.