LILY-925 Rework Solr exception handling

Don't retry solr operations in the SolrClient, instead throw
applicable exceptions up the stack and let the SEP take care of
retrying.

Small changes to forked version of ReplicationSource to make up
for pending HBase JIRA tickets (HBASE-7325 and HBASE-7634).

Update documentation to use correct definition of SEP (Side-Effect
Processor).