Review log4j.xml and significantly reduce logging level

[jamoore]

The logging level is definitely affecting performance. Just how much isn't completely clear yet, but it's certainly a lot (in fact, the calls to log4j can hang the entire server if standard out doesn't flush fast enough).

See #725

[cxallan]

We should also look into ensuring that:

• there are no e.printStackTrace()'s anywhere (they just make debugging using the server.log kinda impossible)
• instances of System.err or System.out are removed from the codebase

[jmoore]

Replying to callan:

We should also look into ensuring that:

• instances of System.err or System.out are removed from the codebase

See #383

[jmoore]

The plan:

• port etc/log4j.properties to etc/log4j.xml -- this allows more consistent reuse between blitz and jboss. This requires modifying omero/java.py to set -Dlog4j.configuration=file:etc/log4j.xml since the default log4j configuration searches for log4j.properties.
• reduce logging as much as possible -- since our error handlers log all exceptions levels can be significantly reduced. Also, having them explicitly listed allows users to more easily selectively increasing logging later if problems arise.

[jmoore]

r2799 contains this fix. WebAdmin? still has its own log4j.properties file (for creating JBOSS_HOME/server/default/log/WebAdmin.log) and so shouldn't be affected by this change.