Sync strutils from oslo

Sync strutils from oslo which fix safe_encode under py3, this gets
heat CLI to not output in bytes.

(there is a bit more to be done for complete py3 support)

84d461 Fix a bug in safe_encode where it returns a bytes object in py3

Change-Id: Ic29c0037bfbc612e954045c95edca68f273c4a1a
Merge "Sync strutils from oslo"