Moqui now honors the standard Log4j property 'log4j.configurationFile'

[jmochel]

Intention:

To give developers the same level of control during logging of components and the framework they have in other products using Log4j.

What it does:

This change replaces the use of the hard coded log4j.xml from the jar resources with

1. A use of the contents of the standard Log4J configuration file override property (log4j.configurationFile) from system properties or environment variables if it is set in either.
2. If no location is found, it tries to find "log4j2.xml" on the classpath (basically, as a resource bundled with the code or libraries).
3. If it can't find a configuration file in either location, it logs a warning and stops (does not attempt to reconfigure

[eigood]

It might be nice to see several layers of initialization. The initial bootstrap, where a very simple log4j config is loaded. Then, after all MoquiConf.xml snippets are loaded and merged, it(log4j) gets re-initialized.

[schue]

Typically log4j.configurationFile allows multiple files separated by commas.

If the file doesn't exist it will still try to load the file. A File.exists() that logs a warning if it isn't there would be more defensive.