build: Support gmime 3.0
build: Support gmime 3.0

And remove support for gmime 2.4 from 2012.

MikePetullo/grilo-plugins,GNOME/grilo-plugins,grilofw/grilo-plugins,MikePetullo/grilo-plugins,MikePetullo/grilo-plugins,jasuarez/grilo-plugins,GNOME/grilo-plugins,jasuarez/grilo-plugins,grilofw/grilo-plugins