Another attempt at upgrading to Babel 7

[nathanfriemel]

Upgraded all 'babel-' dependencies and various other dependencies that were still using babel 6. Then worked through the issues that came up:

Updated eslint to latest version that uses babel 7 and converted .eslintrc(s) from yaml to json.

Use strict now uses double quotes instead of single quotes; see this.

Ava was updated to a newer version that uses babel 7, it’s actually using rc1 since even version 0.25 was still using babel 6. For the tests this caused a change where the process.cwd() is now wherever the package.json is located when running tests; see this thread. This lead to changing all the tests config paths, removal of the ‘basic require with default webpack name’ test (for now, open to suggestions on how to re-add) and changing a lot of the expected fixture paths.

Expected fixtures are now double spaced to match generated output and paths that are replaced become double quoted, not sure why couldn’t find documentation on that one.

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@cb486b7). Click here to learn what that means.
The diff coverage is 100%.

@@            Coverage Diff            @@
##             master      #59   +/-   ##
=========================================
  Coverage          ?   94.38%           
=========================================
  Files             ?        1           
  Lines             ?       89           
  Branches          ?        0           
=========================================
  Hits              ?       84           
  Misses            ?        5           
  Partials          ?        0

Impacted Files	Coverage Δ
src/index.js	94.38% <100%> (ø)

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[nathanfriemel]

Node.js 4 build is failing, according to this babel 7 has dropped support for Node.js < 6

[nathanfriemel]

Closing this pull request because it's not getting any traction, I've also begun work on @babel/plugin-webpack-alias as a babel7 replacement over at https://github.com/shortminds/babel-plugin-webpack-alias if anyone is interested.