Updated "i18n fix" / Migrate to Babel 6

[maullerz]

This pull request forked from @thaerlabs PR "i18n-fix" #119 With additions:

• [x] upgraded tests with loop over array of locale-values
• [x] applied feedback from @wmertens
• [x] completed migration to Babel 6
• [x] upgraded test loader from isparta-loader (deprecated) to babel-plugin-istanbul
• [x] a bit of eslint fixes

Deployed and working on my gh-pages - https://maullerz.github.io/react-daterange-picker/

I am using react-daterange-picker in production from forked repo now.

About squashing PR commits: https://help.github.com/articles/about-pull-request-merges/

You can merge pull requests by either
retaining all the commits in a feature branch
or by squashing all commits into a single commit.

[maullerz]

bump @AlanFoster pls check this

[maullerz]

PR description updated @AlanFoster need your attention Travis CI failed because of upgrading eslint and gulp-eslint. https://github.com/adametry/gulp-eslint/issues/161 ESLint v3.0.0 now requires Node.js 4 or higher.

Travis here have 0.12 node version.

What should i do with this?

[andywer]

@maullerz It's not my repo, but I would suggest dropping node 0.x support. Requiring node 4+ should be fine.

How about throwing 0.12 out of the .travis.yml and adding "engines": { "node": ">= 4.0" } to package.json? The build will be green and if someone's still running 0.12, npm will show them an error :)

I hope @AlanFoster will merge it soon if the build is green.

[maullerz]

@andywer thanks for bump 👍

[andywer]

@maullerz Took the chance to try the new PR review feature 😉

[AlanFoster]

Awesome; Thanks @maullerz

[andywer]

@AlanFoster Could you please publish the updated package? :)