Switch rally.sshutils from 'eventlet' to 'time'

Inasmuch as tests.test_sshutils.SSHTestCase.test_wait and
test_wait_timeout fail on py26 on Mac OS, it was decided to remove
'eventlet' from sshutils and instead of it use 'time' module and it's
same functions.

Change-Id: I7d0ae176b0419e09157c09d7c6213edc109df2e0
Closes-Bug: #1264403
Merge "Switch rally.sshutils from 'eventlet' to 'time'"