Allow disabling of debug logging

I find that enabling the debug log level often causes me to miss
important error messages due to the sheer volume of information
logged.  This change allows configuration of the debug option
in a number of the projects so it can be disabled globally
without having to make one-off changes after each re-stack.

Note that this does not apply to Keystone or Swift right now.
They use a different method to configure their logging level and
I'm not as familiar with them so I didn't want to mess with their
settings.

Change-Id: I185d496543d245a644854c8a37f3359377cb978c
Merge "Allow disabling of debug logging"