This should get Geary ready to be integrated into l10n.gnome.org,
GNOME's Damned Lies translation project. The biggest change is that we
no longer track a .pot file, but we set it up so that translators can
generate their own using intltool-update --pot.
Closes: bgo #713827
./configure will autodetect xgettext, and if available, "make pot_file"
will generate the po/geary.pot.
This does *not* include intltool support, so the .pot file only
contains strings from the source files.