Revert "use modern paramiko"
Revert "use modern paramiko"

This reverts commit 76e1b093354dd31d94dd56299d1a245ff82db72e.

I see lots of these failures:

2015-09-06T00:02:43.199 ERROR:paramiko.transport:SSHException: Key-exchange timed out waiting for key negotiation

ktdreyer/teuthology,dmick/teuthology,ceph/teuthology,dreamhost/teuthology,dmick/teuthology,SUSE/teuthology,ceph/teuthology,SUSE/teuthology,caibo2014/teuthology,dmick/teuthology,dreamhost/teuthology,robbat2/teuthology,robbat2/teuthology,caibo2014/teuthology,SUSE/teuthology,ktdreyer/teuthology