ZMQ_STREAM incorporated

Tested for ZMQ_STREAM in zsocket_type function.

Changed variable name interface to iinterface, char* to const char* to
allow compilation with MSVC 2012

Signed-off-by: Gavin <gavin@mcniff.ie>
Merge pull request #203 from gavinmcniff/master

Incorporation of ZMQ_STREAM socket type