ElasticSearch support for translation memory

Boostrapping and live updates work. Translation memory does
return suggestions but quality not verified.

Small refactorings here and there:
* MessageHandle: new utility methods
* Added retrying to multiple places
* The failed http requests went away by refactoring the bootstrapping
  to happen after forking.
* Format of batches changed: MessageHandle, source language, text
* Hackish way to send output to the maintenance script
* Force profiling off to avoid huge memory use

Change-Id: I7013ee35a0e9cb2ef656072da399b1420521b780
Merge "ElasticSearch support for translation memory"