* [grunt/eslint] fix precommit linting
- remove use of `minimatch.makeRe()` because it does not support the entire glob syntax
- log a warning whenever a js file is excluded by the `lintStagedFiles` task
- eslint globs are relative to the project root, ensure that we check against relative version
* [grunt/eslint] only log warning wtr grunt paths
* upgrade eslint, all related deps, and config files
* replace gruntify-eslint with basic eslint-cli wrapper
* arrow-IIFEs must be invoked outside of the parens
* move import statements before their use
* reindent to satisfy new indentation check algorithm
* place missing semicolon
* ignore copy-pasted decode geohash code
* [grunt/eslint] fix argument spacing
* [gurnt/eslint] add comment about contents of report
* [grunt/tasks] use `export default`
We limit the amount of moving parts when it comes to parsing our staged
files in git by reusing the files_to_commit utility rather than the
now-defunct collectStagedFiles task.