Move coffeelint settings to external file

The motivation is for this is to allow `coffeelint` config to be shared by
`script/grunt coffeelint`, global `coffeelint` and inline linting via
`AtomLinter`.

Test Plan:

Made some deliberate lint errors then ran `script/grunt coffeelint` and
verified the output looked the same with and without this change.
ignore no_unnecessary_fat_arrows too
Use grunt-coffeelint@0.0.13 instead of forked version

Test Plan:

```
$ ./script/grunt coffeelint
Running "coffeelint:src" (coffeelint) task
>> 80 files lint free.

Running "coffeelint:build" (coffeelint) task
>> 23 files lint free.

Running "coffeelint:test" (coffeelint) task
>> 40 files lint free.
Done, without errors.
```
Merge pull request #3218 from dmnd/coffeelint-config-file

Move coffeelint settings to external file