[Telepathy] Geolocation in Telepathy

[Simon McVittie]

I posted this on #geoclue already, but here's my initial proposal for
geolocation in Telepathy:

http://monkey.collabora.co.uk/tp-spec-smcv-geoloc/

I decided to go with the "one big dictionary" approach. I've assumed
that you won't define keys in the address dict that conflict with
XEP-0080, and added three new keys: climb, accuracy and alt-error.

    Simon