GEOMESA-164 

adding geomesa pages to geoserver - accumulo stats, hdfs stats, hdfs config, initiate m/r jobs
I added a test against mini-accumulo. It takes ~10 seconds to run...
I tried it with the regular mock accumulo connector, but that doesn't appear to simulate the metadata table.
I didn't back-port it to the accumulo 1.4 branch, as mini accumulo doesn't exist there. However, the risk of the metadata table changing in 1.4 seems insignificant.