setting the logging level

[zytegalaxy]

In ubo.logging.py the logging level if hard coded. For release build, we need to set a different level of debugging.

stdout_handler.setLevel(logging.DEBUG)

Probably need to define a way to set this.

[sassanh]

We already have an environment variable for this purpose, it is UBO_LOG_LEVEL
I reduced the default verboseness of the application, but one has the option to increase it using UBO_LOG_LEVEL.
Is it enough or do we need more?