Adding (hidden) demo for wikitables parser

[matt-gardner]

This adds a demo for the wikitables parser. It's currently hidden, as it could be made to look nicer, and we're still wanting to improve the model a bit. I'm doing this now so that @kl2806 has an example to look at for building a demo for his in-progress ATIS model.

[matt-gardner]

@schmmd, who's the right person to review this PR? And is there a way to see the demo that's produced by this, or does that just go to staging after the PR is merged?

[schmmd]

@matt-gardner you can assign it to me or Joel. I wasn't sure it was ready for review.

Will we need the JVM dependency when we ultimately have the semantic parser demo? ;-(

It's pushed to staging once it's merged. If you want to see the demo, it's best to run the Dockerfile locally.

[matt-gardner]

Yes, we'll need the jvm dependency, as it's required for wikitables. I'm surprised it wasn't already there - we're using Dockerfile.pip for what gets pushed to the allennlp docker repository?

[schmmd]

@matt-gardner Dockerfile.pip just installs AllenNLP via pip. We do bake the JVM into our Dockerfile that is used for continuous integration.