Handle SOLR connection issues gracefully

[prateek05]

At times when SOLR Calls land in

1. Unable to reach host
2. Unable to resolve DNS name
3. Unable to get a response
4. Request Timeouts

The error should be passed to ulog and warnings formatted and passed to the session pane ?
refer #2303

[gordonwoodhull]

Hopefully this will be improved by the rcloud.solr rewrite.