Rematch: Look into using rollup for builds

[ShMcK]

https://github.com/rollup/rollup

[ShMcK]

Ran into an issue with bundling the babel polyfill.

Issue:

• generators need to work
• transform-runtime doesn't work on react-native
• babel polyfill is heavy, and causes issues if loaded more than once
• babel polyfill is not easy to load with rollup

I'm not as yet sure what the best solution is. But it should:

• [x] load generators & other es2015+ features
• [ ] be small as possible

[ShMcK]

May no longer be necessary. Now builds alright on react native with a subset of "babel-transform".

The key is in .babelrc:

["transform-runtime", {
      "polyfill": false,
      "regenerator": true
    }]