Included unistd.h for successful Linux compile, known fix from...

Included unistd.h for successful Linux compile, known fix from https://github.com/open-ephys/GUI/pull/150

Resources/Matlab/unix/zeroMQwrapper.cpp

@@ -13,6 +13,8 @@
 #include <queue>
 #include <list>
 #include <pthread.h>
+#include <unistd.h>
+
 
 typedef struct {
     const char *connect_url;