First stages of revamping logging
Tell PowerMock to ignore class loading for javax.management. Upgrading logging appeared to introduce linkage to an MBean with a different version than Powermock expects. We now just ignore the whole javax.management package for testing because it is not used as part of the tests anyway.
Added guava dependency
Added per-request UUID to logging via Log4j MDC, supported by SLF4J
Fixed up log4j2 config file. Added .DS_Store to .gitignore