Upgrade prettier to 1.7.0

[ppvg]

Upgrade prettier to 1.7.0 to help fix prettier/prettier-eslint-cli#105.

Some tests were (already) failing with:

JSONError: JSON Error in /Users/ppvg/github/prettier-eslint/mock/package.json:
Unexpected token 'v' at 1:1
var fake = true
^

So the fs mock now matches on filename and returns either the original fake or a fake package.json. I'm not sure whether that's considered too ugly of a hack.

[codecov-io]

Codecov Report

Merging #125 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #125   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           2      2           
  Lines         191    191           
  Branches       32     32           
=====================================
  Hits          191    191

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b1c4ba4...0b486fa. Read the comment docs.

[kentcdodds]

Looks great to me! Thanks!