[geode] Ensure geode client will work with v1.3 by removing references to internal classes (#1069)

* Geode 1.3 changed some of it's internals. The geode binding was using an
internal Geode class which means it won't compile against later versions
of geode.

* Based on review comments, leaving the geode version alone and adding
documentation to the README on how to change the version.

* Removed incubating from the geode name and website in README, because
geode is no longer incubating.