Add no-var to eslint

[dplewis]

I used eslint --fix for this.

The only real change was in the promiseUtils.js file

[codecov]

Codecov Report

Merging #710 into master will not change coverage.
The diff coverage is 91.51%.

@@           Coverage Diff           @@
##           master     #710   +/-   ##
=======================================
  Coverage   88.57%   88.57%           
=======================================
  Files          53       53           
  Lines        4535     4535           
  Branches     1052     1052           
=======================================
  Hits         4017     4017           
  Misses        518      518

Impacted Files	Coverage Δ
src/ParseConfig.js	87.5% <100%> (ø)	⬆️
src/StorageController.default.js	100% <100%> (ø)	⬆️
src/Parse.js	84.61% <100%> (ø)	⬆️
src/encode.js	100% <100%> (ø)	⬆️
src/ParseGeoPoint.js	95.45% <100%> (ø)	⬆️
src/ParseRole.js	80% <100%> (ø)	⬆️
src/equals.js	100% <100%> (ø)	⬆️
src/CoreManager.js	100% <100%> (ø)	⬆️
src/arrayContainsObject.js	100% <100%> (ø)	⬆️
src/StorageController.browser.js	100% <100%> (ø)	⬆️
... and 27 more

---

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 629a550...50b8eea. Read the comment docs.