Client dependency updates, move to TypeScript

[neodescis]

Done:

• Updated routing to use react-router 4.x
• Added stylelint
• Updated to gulp 4
• Migrated to TypeScript
• Updated .eslintrc to support change to TypeScript
• Updated most libraries to @latest
• Updated README

Still to be done:

• I didn't enforce types on the actions accepted by the reducers, as it didn't seem worth the trouble, but it might be worth doing at some point
• Update redux-form to @latest
• Bring back bootstrap-loader if/when it is compatible with Webpack 4 (using a CDN to retrieve the styles for now)
• Upgrade redux to v4 when redux-thunk's typings are compatible with it

resolves #38 resolves #39 resolves #31

[neodescis]

K, I think the PR is ready. Let me know if you see anything that needs attention. I managed to get bootstrap-loader working again. Apparently switching to TypeScript broke HMR, so I got that working again last night.

[pauldotknopf]

I finally got around to look at this, and I am very thankful! You did a lot of amazing work.

Once it's merged, I'll give you a by-line.

I'd love to buy you a beer. Got a PayPal? Email it to me, if you like.

[neodescis]

Ha, not a problem, it's been my pleasure. Glad to give back! You've done really excellent work yourself, especially with the underlying view engine. I'm happy to accept a beer. I appreciate the gesture; I definitely wasn't expecting anything in return :-)