Documenting broken method

YamClientPool.connect() is solid, but the underlying implementation
leaks connections. When that bug is fixed, YamClientPool.connect() will
start working again, so I'd rather not take it out at this point.
Handle cancel of getConnection

getConnection() should be cancellable
Adding auto-pruning for connections in the pool

Also added tests in autoinc.py
Add autoincBy and autoincTimeout as parameters to YamClientPool
Restructuring test_autoinc to work with pruning