1.2.0

This new release backport stuff from the main fork of Sonerezh. A big thanks to
the community, and @gs11.

Bug / Security fixes:

• Merge #339: Time to merge (thanks to gs11)
• Merge #318 (fix #277): Getting "Undefined index: id [APP/Model/User.php, line
  152]" During Installation (thanks to GaneshKandu)
• Merge #312: Player now shows artist instead of band
• Merge #309: Fix related to MySQL and SQLite
• Merge #306: Upgraded CakePHP to 2.9.8 (thanks to gs11)
• Merge #304: Changed select grouping so that albums with the same name are
  listed
• Merge #300: Removed slow subquery from album view
• Merge #293: Implemented database cleaning
• Merge #287: Removed trailing slash in subdirectory path added by CakePHP for
  some folders
• Fix #263: Something wrong with files with non-latin characters in name
• Fix #241: Install script doesn't create the database
• Fix #214: Optimization: enable caching for albums covers (thanks to
  MightyCreak)
• Fix #152: IndexedDB does not function in private browsing mode (documentation
  improvement)
• Fix #107: Replace avconv with ffmpeg

Fixes from gs11's fork:

• Fixed detection of tag 'DISCNUMBER' without 'DISCTOTAL' for OGG files
• Fixed detection of disc number without a disc total in the string (e.g. '01'
  instead of '01/02')
• Fixed year not showing for album with multiple CDs

New features

• Merge #293: Implement database update (thanks to gs11)
• German translation (thanks to soulsymphonies)