Better logging configuration for the build master

[cmlenz]

The build master script provides three options for controlling the amount of logging generated:

• The default log level is logging.WARNING
• --verbose or -v maps to logging.INFO
• --quiet or -q maps to logging.ERROR
• --debug maps to logging.DEBUG

However, logging in Bitten is still rather limited:

• All messages are sent to the root logger
• There's no way to configure log handlers (e.g. log to a file, syslog, etc)
• The format of log messages is the default, very basic style
• Log messages from Trac are interleaved into the messages generated by Bitten, and disregard the configured log level because Trac has its own logging configuration.

Because the build master is intended to be run as a daemon/service, it is important that its logging capabilities are improved.

[cmlenz]

Doesn't block 0.2, so postponing.

[cmlenz]

Fixed in [98].

The various Bitten modules that do logging no longer log to the root logger, but rather to a logger named "bitten.xyz".

For the master, a formatter is installed that just outputs the log message to the console with no extra information to the console, and (optionally) with more information to a log file.

The Trac log messages only go to the Trac log file, if configured in Trac.