[Build] Dependency updates

Gradle: 2.0
Nifty-GUI: 1.4
[Download] Only accept SNAPSHOTS from illarion repo for dev builds
[Client] fix name of mac installer
[Nifty-Controls] Changed color of description in container to white
[Build-Tool] Fixing compatibility to new groovy version
[MapEditor] Properly handle missing graphics
[Build] Updated some dependencies
[MapEditor] Removing useless dependencies
[Build] Updating resources version
Merge branch 'release/2.1.16'
Merge branch 'release/2.1.16' into develop
[Build] Updating resources version
Merge branch 'master' into develop
[Downloader] Use a directory in the home of the user as storage

That is an alternative to the storage in the installation directory.
The storage in the installation directory is preferred. But if it
does not work for some reason it falls back to this alternative storage.
[Downloader] Fixed creation of desktop, quickbar and dock launcher
[Downloader] Fixed java launch path
[Installer] Fix corrupt OS X icons file