Bumped version number for next release, 2.0.1
Updated CZMQ to work with ZeroMQ 4.0

* All socket options as implemented by ZeroMQ/4.0.0
* Removed deprecated zsockopt_set_xxx macros
* Added macro capability to scripts/sockopts.gsl to save code duplication
Merge pull request #235 from hintjens/master

Updates for ZeroMQ/4.0.0