Create an endpoint to ingest raw json

[afoerster]

The current endpoint requires the json payload conform to a LogEvent type. This LogEvent type has data needed for log4j or Python logging, but isn't flexible if we want to insert arbitrary data, like Metrics, into Pulse.

• Create a new endpoint in LogCollectorRoutes with the path `v1/json/
• Parse the json using Spray (this is already a project dependency) into a map[String, String]
• Change all code in SolrCloudStreams to work with Map[String, String] instead of LogEvent. Figure out: do we still need the LogEvent class? How can we move it up the call stack?
• The new endpoint should dump the Map[String, String] onto the solr stream.
• At the end of the stream here: solrService.insertDocuments(latestCollectionAlias, events.map(DocumentConversion.toSolrDocument) we need a function to convert the Map into a SolrDocument