[lib/Twitterizer] Updated to fix a build issue on Mono 3.0
[Build] Added src/Engine-Campfire/ to POTFILES.skip where needed
[Build] Ignore temporary build files in debian/
[Build] Ignore source file for translations

gettext believes this file contains translatable strings but it does not.
[Build] Fixed make distcheck on systems without libmessaging-menu-dev
[Build] Run make distcheck for Travis CI builds
[Build] Run unit tests for Travis CI builds