add method to get CC sha1 for cf-release version
update to proxy specific version of cf-release

pass ?version=192 to get the version

Cookie stores most recently requested version.

Hard-coded all known versions. It will discover at
runtime any unknown versions and cache these for
future requests.

Specifically excluded v194 to demonstrate discovery.

TODO: Discovery might be better to be on offline process,
which populates a Redis DB. Caching is stored in process,
so *not* horizontally scalable.