Change logging framework to Logback and provide autoconfiguration

[stephanr]

Change the logging framework from log4j2 to Logback by providing a deegree module that provides configurators for Logback.
This is done by registering a java style deegree default configurator class beside the regular Logback file-based configurator.

So if no Logback configuration was added to the war or configured with a system parameter or environment variable, the deegree auto configurator kicks in and configures console- and file-logging as well as the levels.

This is not yet finished, as the documentation is work in progress and the default settings are not final yet.

TODO:

• provide section about using a different logging implementation

fixes #1248
closes #1705

References:

• Reevaluate the use of log4j within the deegree project #1248
• Create new module deegree-core-test-logging, add test-logging dependencies and remove log4j2.properties in test modules #1704
• Change logging framwork from log4j2 to logback #1705

[tfr42]

Also relates to issues #1782 and #1251.