reprepro: import from elasticsearch/logstash apt

elasticsearch.org now provides apt repositories, as of Dec 20th:
http://www.elasticsearch.org/blog/apt-and-yum-repositories/

For Elasticsearch, we use their 0.90 packages anyway, so it's a
no-brainer: import future versions from their apt, no functional
changes.

For logstash, it's a bit more complicated: the packages that we
currently have in apt seem of better quality than the ones in
Elasticsearch's apt repo. However, it probably makes more sense to use
upstream's and file bugs with them so they can improve their official
packages instead.

Change-Id: I748d45df3b216f0ae38ce84a0adfe761175b3b1d
Merge "reprepro: import from elasticsearch/logstash apt" into production