Build ES and point jsnext correctly

[rehandalal]

I am having issues with the current build and ESLint.

Due to an incorrectly configured jsnext in package.json I get:

error  Unable to resolve path to module 'redux-form-material-ui'  import/no-unresolved

This fixes the issue.

[codecov-io]

Current coverage is 100% (diff: 100%)

Merging #32 into master will not change coverage

@@           master   #32   diff @@
===================================
  Files          19    19          
  Lines         267   267          
  Methods        62    62          
  Messages        0     0          
  Branches        4     4          
===================================
  Hits          267   267          
  Misses          0     0          
  Partials        0     0          

Powered by Codecov. Last update 842b2f6...8ef414f

[erikras]

Published in v4.1.0.

[danny-andrews]

This is incorrect. pkg.module (i.e. pkg.jsnext:main) should point "to a module that has ES2015 module syntax but otherwise only syntax features that the target environments support." https://github.com/rollup/rollup/wiki/pkg.module