Triangle facts 20140929 rc

Updates:
-`sides` method created and used where applicable
-variable renaming in `calculate_angles` method

Side note: this led to the lines being longer than 80 chars, so i broke the lines out based on this style guide: https://github.com/thoughtbot/guides/blob/master/style/samples/ruby.rb#L62-L66

@bwthomas Is this type of formatting acceptable/practiced in the Enova coding environment?