Accumulo Mini Cluster for local integration testing

There is no 1.4 branch for this... mini cluster doesn't exist in 1.4.

The mini cluster is a new module, but is not added to the parent pom so that it doesn't get built automatically.
log4j and slf4j-log4j12 aren't used in any of the other modules. I included them here because that was the only way I could get control over the zookeeper logging messages. I did re-use the ${slf4j.version} property from the parent pom.