add search rules for eQTL and gene_trait queries

[yudongqiu]

This addresses later task in #118
Token eqtl is added to find all SNPs influencing to a certain gene.
Token genes is added to find all genes that are intersecting with all variants that are influencing a certain trait. (There is a small issue that the keyword genes will pop the geneNames as choices due to regex matching. It may be solved by using a "unique" keyword, but I'm not exactly sure what is a good keyword)

This PR also refactors the existing building query functions using the QueryBuilder class.

[yudongqiu]

I think the tests are failing because of the jest configuration but I'm not sure how to fix it.

[saliksyed]

Nice work @yudongqiu -- it appears to me the QueryBuilder js file is not properly being consumed by the typescript processor (querybuilder is written in TypeScript not plain javascript):
wmonk/create-react-app-typescript#122

So the way it works is:
All imports in TS files are fed through the typescript pre-processor to compile from ES6 -> vanilla JS. In this case it seems that this pre-processing is not taking place for that particular file, so the raw es6 file is being included (which contains keywords like "export" that don't work in vanilla js).

I checked out your branch and can replicate the error by running npm test, I'm playing around with it to see if I can get it to compile, but I think it's a path issue with the jest config as you pointed out. I just realized you have never worked with TypeScript before I assigned this task!

[saliksyed]

@yudongqiu -- don't spend time on this -- it's a nasty config issue. I will try to fix it.

[saliksyed]

The fix is to switch this line:
'^.+\\.jsx?$': 'babel-jest',

TO:

'^.+\\.jsx?$': 'ts-jest',

The babel compiler isn't correctly configured to ingest es6 files which is why it breaks. The ts-jest compiler is already configured to do this so I'm not sure why we even had babel in the first place.

[saliksyed]

LGTM @yudongqiu

[saliksyed]

@yudongqiu with the rebase this should just work -- as we are no longer using the babel compiler