Add GLIB version guards

-Make sure we don't use any new features above GLib 2.30
-Ubuntu 12.04 uses glib 2.32.x which requires GLIB_VERSION_2_26 to
 be the smallest compile target -> bump minimum version to 2.26
Fix test execution problem on openSUSE

For some reason, locking across two calls was not working on openSUSE-based
systems. This change replaces the simple lock scheme with a condition-based
approach.
Abstract away communication into interface

* Create generic interface ufo_messenger_iface
* Move all zmq_* stuff into ufo_zmq_messenger that implements that
  interface
* also fixes a bug that happened when closing the zmq_socket from
  another thread by introducing a special TERMINATE message that
  will kill ufo-daemon
Fix bug: no plugin name is sent to remote nodes
Add MPI support
Merge pull request #4 from Dynalon/master

MPI pull request