Enable actual spawning

still needs tests and a functional Resque connection
Allow for configurable redis endpoint
Move worker_base_spec to the correct location
Don't use method_missing.

Forward the methods instead to the process
Rearrange methods in WorkerGroup
Implement Pool#despawn!; fix Pool#spawn
Initial doc for Manager
Initial doc for WorkerGroup
Initial doc for Pool
Fix documentation for attr_* and hattr_*
Initial doc for Queue
Registry is now a Mixin, not a Class

RedisRegistry no longer inherits methods from the memory-based Registry
class. Methods with common implementation are stored in the Registry
module, and the contents of the class have moved to MemoryRegistry
Initial doc for Registry module
Fix source of TTL for expiring spawn_blocked key
Initial doc for RedisRegistry
Initial doc for Worker
test the actual RedisRegistry class
Remove MemoryRegistry

Don't need to maintain a second Registry class now that we are mocking
Redis.
use REDIS_MOCK instead of $redis_mock

to store the mocked Redis instance
Those tests I've been promising