Code cleanups

- please do not use Tabs for indentation (read CLASS style guide)
- moved long list of prime numbers to separate header file for ease
  of reading zhash.c.
Fixed include path for czmq.h
Rewrote zmonitor to use zactor

- renamed existing zmonitor -> zmonitor_v2
- renamed zsock_monitor -> zmonitor
- related cleanups in zauth
Merge pull request #594 from hintjens/master

Rewrote zmonitor -> zactor for CZMQ v3