update .gitignore
logger: prepare GROUP if needed

GROUP is no longer a part of CORE so we have to prepare it manually.

I did a similar change in Empathy see
https://git.gnome.org/browse/empathy/commit/?id=84e5c73bbf88e85387f4ab8dbcad569b3f571a91
SPEC: copy Logger1 from tp-spec
Logger1.xml: add to EXTRA_DIST
add logger.xml
doc: add logger types and iface
logger: generate server side API
logger: use tp-glib generated svc code
logger: stop generating D-Bus API as an extension
interfaces: add logger bus name and path
add TpLogger and generate client side API

TpProxy sub-class which will be used for generated client side API.

I just implemented the simpler constructor for now as that's all Empathy
needs.