pidgin/pidgin

Propagate the notify signal for the Presence object on a ContactInfo

Testing Done:
Ran the unit tests under valgrind and verified now no leaks.
Also checked the docs and made sure the signal was documented properly.

Reviewed at https://reviews.imfreedom.org/r/2306/
i18n = import('i18n')
# use the glib preset which is defined at
# https://github.com/mesonbuild/meson/blob/master/mesonbuild/modules/i18n.py#L93
# at the time of this comment.
i18n.gettext('pidgin', preset : 'glib')