Update exhibit.rb

Checking for class name before downcasing. 

classes returned from <code>view_context</code> call in controller are anonymous and respond with nil when asked for their name.
add test that ensures .exhibit works when passed a context that is an instance of an anonymous class
Merge pull request #1 from codeodor/patch-1

Add test that ensures .exhibit works when passed a context that is an instance of an anonymous class
Merge pull request #36 from amaierhofer/patch-1

Update exhibit.rb to include a check for anonymous classes before trying to operate on it's name.