Added TCP connector testing script.

Usage is similar to the HTTP connector testing script. Go figure.
Whoops...
Added basic reply validation.

Ensures that the returned message is, in fact, what we expect.
Fixed a deadlock when adding new TCP workers.

Adding TCP workers while there were any ongoing requests resulted in a deadlock because the worker became rented before it could finish adding itself to the connector pool.
Fixed a possible checkout/checkin deadlock.

Since pending requests are dispatched on checkin, having checkin wait for result might have deadlocked the caller.
hive_connectors pool exhaustion bug workaround.
Merge branch 'idorobots/connectors-revamp' into idorobots/tcp-worker-fix
Tiny fixes.
Fixed the comments.
Merge branch 'idorobots/connectors-revamp' into idorobots/tcp-worker-fix
Merge pull request #10 from brainly/idorobots/tcp-worker-fix

Fixes various deadlocks & other issues in the TCP Connector