Add lib folder to system path for replace_osd action

The replace_osd action fails to run because the ceph import cannot
be resolved without the lib folder existing in the system path.

Change-Id: If85a3ac7edbb22abf11cff5429e6820322ded898
Closes-Bug: #1696958

actions/replace_osd.py

@@ -18,6 +18,7 @@ import os
 import sys
 
 sys.path.append('hooks/')
+sys.path.append('lib/')
 
 from charmhelpers.core.hookenv import action_get, log, config, action_fail