mailnag-1.2.1-bp153.1.13

- Correct licence, it is GPL-2.0+.
- Fix dependencies.
- Separate localisation into mailnag-lang package.
- Remove categories alteration: fixed upstream.
- Don't set CFLAGS environment variable: nothing uses it here.

- update to version 1.2.1
  * Improved GNOME-Software integration
  * Fixed missing plugin config dialogs in Ubuntu 14.04
  * Fixed IMAP idle folders issue
  * Fixed GTK warnings
  * Misc other fixes and improvements
  * Updated translations

- initial packaging of version 1.2.0