Fixed minor issues with folder change

- Tests passing in MATLAB + Windows
Added class Scoket with initial support

Missing:
- send/recv
- tests
Added basic tests to zmq.Socket

Right now they were just copy/pasted from core api, with minor changes.
There are a better way to test, avoiding this duplication?
Improved socket closing
Merge pull request #16 from abravalheri/fix-test/fancy-api

Fixed minor issues with folder change
Added send/recv support to zmq.Socket
Merge pull request #17 from abravalheri/fancy/socket

Initial fancy socket implementation from @abravalheri
Merge pull request #18 from abravalheri/fancy/socket

Add send/recv support to zmq.Socket