pidgin/pidgin

Create a proper GtkApplication subclass for Pidgin and use it.

Testing Done:
Compiled and ran, tested irc and bonjour.

Reviewed at https://reviews.imfreedom.org/r/155/
---
name: libpurple-common
buildsystem: simple
build-commands:
- true
modules:
- external/avahi.yml
- external/cyrus-sasl2.yml
- external/farstream.yml
- external/libgadu.yml
- external/libidn.yml
- external/mercurial.yml
- gplugin.yml