Use videolan.org to download VLC

It looks like VLC 2.0.7 isn't on sourceforge yet, or at least the files
section of the project is unavailable. We can point to the actual VLC
site for downloads.

Fixes #515
Merge pull request #516 from fanquake/update-vlc-url

Use videolan.org to download VLC
Add Opera Mail v1.
Add a cask-file for TestFlight 1.0_beta306
Merge pull request #507 from jstallings/testflight

Add a cask-file for TestFlight 1.0_beta306
Merge pull request #517 from mrben/opera-mail

Add Opera Mail v1.