Upgrade to Elasticsearch 5.0.0

[puug]

Main changes

• Upgrade to Elasticsearch 5.0.0
• Upgrade to Kotlin 1.0.4

Other changes which can be revoked:

• Slight change in pattern where instead of specifying enums, use plain strings to make the DSL more like the JSON counterpart. I see the argument both ways, and I've only incorporated where I've had to fix breaking changes.
• Introduced CommonQuery which allows for common functionality found in AbstractQueryBuilder which all queries inherit from. Specifically this allows for 'boost' args and application to be applied to all inheriting queries, but at the cost of no longer being able to use data classes. Only applied to the term queries for now, but this pattern can be used elsewhere.

[mbuhot]

@puug: Awesome! Is this getting some production use? Would you like to transfer this repo to the https://github.com/consoleau org?

[puug]

@mbuhot We're certainly looking at it, even though ES 5.0 is a bit buggy at the moment. We're happy to give it a good home if you're busy drinking the Elixir coolaid 😄