log `ceph --version` when installing 

This should address issue 5617 (http://tracker.ceph.com/issues/5617). Logs the ceph version after installation completes.

It also fixes a problem with the new logging features added, where ASCII colors where being logged to the file (they should not).

This is an example output of the logs:

    [node1][INFO  ] Running command: ceph --version
    [node1][INFO  ] ceph version 0.61.7 (8f010aff684e820ecc837c25ac77c7a05d7191ff)