DS-1241 Statistics Implementation in Elastic Search

Copied in Implementation of Elastic Search, and wired it into DSpace.
I changed the ES Node to be a nodeClient, and also one that runs locally
within tomcat's JVM. For OSU, we had used either transport-client, or
node-client, and both of which required that the server also be running a
seperate elastic search instance. By bundling this into DSpace, it should
make this a bit more turn-key to get started using Elastic Search.

By default, Elastic Search is ON with this commit.
DS-1241 Elastic Search Statistics - Put Mapping/Schema
DS-1241 Modifying the dashboard theme to have working JS and CSS

Currently wiring the dashboard theme to copy-in the style.css that
Reference uses.
Provide a link to the view-elastic-search statsitics view
Proof of concept convert ES response to a neutral data object to spit out JSON

Created a class called DataTermsFacet, which holds list of term:count pairs.
Create importer to ingest dspace.log usages events to ES
Add DSpace licensing to contributed code

mvn install had complained about these files.
Excluding jcl-over-slf4j from sneaking into dependencies

If two slf4j versions (1.6 and 1.5) get into the project, it causes
version mismatches, and you get a dreaded error like:
java.lang.NoSuchMethodError: org.slf4j.spi.LocationAwareLogger.log

Somehow the version bumps I've added to lucene, or other dependencies I've
added have caused slf4j to import jcl-over-slf4j (version 1.6). This fixes
that.
Add sonatype-releases repository for Elastic Search

The elasticsearch jar was in my .m2/repository, after clearing that, I
realized I need to add the sonatype repository.
Simplify ES client creation (Node, Local, Transport), and default to Node

Changed default client to be NodeClient so we can listen to IP transport.
ES stats-import explicitly uses a transport-client

Plus:
- A bug fix where we only execute a bulk-data post, when we have a payload
- Remove userAgent from data, since we can't obtain from dspace.log
Add stats-log-importer-elasticsearch utility to launcher
Remove copy/paste metadataStorage from ES, following DS-421

Stumbled upon strange code, that has a note in DS-421.
Which says metadata storage in usage-event stats engine was inadvertent,
so ES has no need to include this. Note: I haven't touched SolrLogger
Move ES configs into module structure of elastic-search-statistics
Move implementation agnostic usage-stats configs to new config module

Not sure if I need to add usage-statistics.cfg to module overlay pom for filter
Add isUseProxies to SpiderDectector, to remove solr dependency

Also, a fixed a typo in dspace.cfg, no code refers to log.useProxies,
just useProxies.
Refactored ES Stats UI to come from IncludePageMeta, instead of theme
Limit UsageEvents to listen for to just VIEW events

With the advent of Search UsageEvents, we don't want to track searches,
just to track views.
Remove/revert Growth queries

I've removed the growth queries from the stats.
1) These are Usage statistics, the growth information should not reside in
statstransformer
2) It was poorly constructed with direct SQL in the UI layer.
Add code-comment for the ES classes

Also removed an unused function in report generator