Keystone use common logging setup

The Keystone setup was using logging.conf to configure logging,
unlike other projects. This may have been left over from before
Keystone switched to oslo logging.

Switching to common logging configuration allows:
- Common format for logs for easier parsing
- Pretty colorized logs
- Keystone can control the default logging levels for libraries
  that are used by setting the defaults in keystone.
- Potentially using a function to setup logging for all components
  using oslo-logging (e.g., share with lib/nova).

Change-Id: I4e9b1e6cffce30f16a1e039224312852b8abda07
Closes-Bug: #1271775
Closes-Bug: #1269987
Merge "Keystone use common logging setup"