Switch to a pool of synchronous replication threads
Use blocking pops, never wake early
Log for tombstone expiry
Markups
Merge pull request #47 from Metaswitch/no-more-curl-multi

Reviewer Alex - No more `curl_multi`
Commonalize replication function
Merge pull request #49 from Metaswitch/no-more-curl-multi

Reviewer Alex - Commonalize replication function