sync with oslo and use oslo.i18n

- remove strutils and gettextutils from openstack/common
- start use of oslo.i18n

sync to Change-Id: Ia1820495a989f4f84530ab83f2d87d53a9f761df

Change-Id: I7e2ead688ac9fcab0ac6a2479e0eca12af415b07
Fix old-style classes declaration

Change-Id: I8759dd64637e5150f6744d0989eaa5e584487f5e
Merge "Fix old-style classes declaration"
Make methods static where it's possible

Change-Id: If6c1fa05044e65ec1e72a3e5f63e6db826469a2d