Separate test requirements into test_requirements.txt.
DHT._dataStore -> DHT.dataStore
DHT/Transport refactors, updates.

 - DHT on_find_node DRY refactors.
 - TransportLayer/CryptoTransportLayer now destroy ZMQ sockets on shutdown.
fix build

Signed-off-by: Thomas Stilwell <stilwellt@openlabs.co>
Merge pull request #554 from Geekfish/cleanup/split-test-requirements

Separate test requirements.
Merge pull request #558 from benemorius/fixbuild

fix build