Added more information for building from git
Added more information for building from git

Added make vendor-elasticsearch for getting jars out of elasticsearch for running from git.
Aloomaio/logstash-kafka,opentable/logstash-kafka,Aloomaio/logstash-kafka,joekiller/logstash-kafka,tinglinux/logstash-kafka,tinglinux/logstash-kafka,opentable/logstash-kafka,joekiller/logstash-kafka