Update desktop file to fix warnings and deprecations.

Fix warnings provided by the desktop-file-validate tool:

- Encoding key and Application category are deprecated.
- Icons should not have an extension if the path is not absolute.
Merge pull request #2 from graaff/master

Fix desktop file deprecations.
Fixes display [] as text on OSX

Needed new gtk-mac-bundler to correctly generate pango.module.
The launcher script needed to be updated to set the pango paths
Release 1.0.0 stable.