Removed conflicting dependency. Created highly intermittent failure while deploying in travis-ci.

Details are from http://www.slf4j.org/codes.html#log4jDelegationLoop
The purpose of slf4j-log4j12 module is to delegate or redirect calls made to an SLF4J logger to log4j. The purpose of the log4j-over-slf4j module is to redirect calls made to a log4j logger to SLF4J. If both slf4j-log4j12.jar and log4j-over-slf4j.jar are present on the class path, a StackOverflowError will inevitably occur immediately after the first invocation of an SLF4J or a log4j logger.
Merge commit '627113d718c98d14256f057e3ad5eff28a28fa81' into enable-integrationtest