calls fonts erase. fixes #410
Make paperclip_waveform optional

There are problems in some systems, such as Heroku, with the ruby-audio
gem. It requires libsndfile library.

Now this functionality is optional. The paperclip_waveform gem must be
added to the application's Gemfile.

Fixes #407
Add true to respond_to to include protected methods

http://bugs.ruby-lang.org/issues/3562
2.0.1
Merge 'origin/2-stable'

[ci skip]