Dissector for elasticsearch protocol

Provides dissection for the elasticsearch protocol. This includes full
dissection of the multicast discovery protocol, the HTTP query interface
and partial dissection of the binary protocol.

Change-Id: I738fb498976e44fa05168c2bc3a7e842a9e96df9
Reviewed-on: https://code.wireshark.org/review/4948
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>