Added binary data (uint8) conversions
Added size_t conversions
Added zmq_recv, zmq_send
Added test_zmq_req_rep

- Needs to test multipart messages
- Needs to test other socket types
Added tests_zmq_req_rep_multipart
Added PUB/SUB PUSH/PULL examples
Merge branch 'api/messaging-basics' into dev

Conflicts:
	src/core/zmq_send.c

'dev' version prefered, but some changes were needed in order to pass
tests
Merge @abravalheri's commits, adding examples, basic messaging support and more tests.