supporting simple module deployment

this is just a stepping stone commit, still requiring a lot of rework

does not yet support options values, composed modules, jobs, or source/sink channels
Added ZooKeeperStreamDefinitionRepository

That is now instantiated within both redis-store.xml and memory-store.xml.

It will later be expanded to supplant those (the --store option will no longer be necessary).

The /streams endpoints in the REST API are now backed by this implementation.