Updated mvn to include log4j dependency.
Updated mvn to include log4j dependency.

Without this dependency, the simple logging facade for java (slf4j)
used by thrift fails to find a binding, and uses a useless no-op
logging framework.

dmwu/sparrow,dmwu/sparrow,dmwu/sparrow,YanjieGao/sparrow,radlab/sparrow,radlab/sparrow,dmwu/sparrow,YanjieGao/sparrow,YanjieGao/sparrow,radlab/sparrow,radlab/sparrow