Add mkvtoolnix

Homebrew already has formulas for mkvtoolnix but it builds app from sources which include 4 extra depedencies.
I had a problem with building process on my machine so I decided to create cask and use binary files build by Jonathan Buschmann.
Merge pull request #1188 from lucmendelowski/mkvtoolnix

Add mkvtoolnix
Add growler for google-notifier.

Closes #1153

Signed-off-by: Fernando Paredes <nano@fdp.io>
fix super-collider link path