Sync 'loopingcall' module from oslo-incubator

Sync 'loopingcall' module from oslo-incubator

In order to be able to move to using the new log
library we need to update loopingcall to the latest
version.

Current HEAD in OSLO:
---------------------
commit e589dde0721a0a67e4030813e582afec6e70d042
Date:  Wed Feb 18 03:08:12 2015 +0000
Merge "Have a little fun with release notes"

Changes merged with this patch:
---------------------
2fbf5065 - Remove oslo.log code and clean up versionutils API
5985b35f - Prefer delayed %r formatting over explicit repr use

Change-Id: I088007bb56d26357ed7b578ae5a57208a3449782