Added TermVector support

[gmarz]

See issue #519

[Mpdreamz]

@gmarz you managed to get the code generation and such to work! 👍 👍 👍

[gmarz]

@Mpdreamz Yup, it was pretty straightforward after you explained it. Now that we have a baseline for term vectors with this PR, MTermVectors (#507) should be relatively easy to implement. I'm going to try and get that in this week. I'd also like to include some tests as well.

[Mpdreamz]

Im really really glad to hear that it wasn't too cumbersome, looking forward to #507.

[gmarz]

@Mpdreamz Added support for multi termvectors (#507). Still need to add some tests. I also synced my fork, so these commits should be a little easier to merge.

[Mpdreamz]

Hey @gmarz, leaving this open until one of us gets around to adding tests :)

Can't thank you enough for adding support for both of these ! 👍

[gmarz]

@Mpdreamz Added a few base integration tests- should be a good start. Note that I had to add a term vector mapping in the integration setup. I felt the Content field of the ElasticsearchProject type was appropriate.

[Mpdreamz]

Thanks @gmarz :)