coffeelint.json had some rules set to ignore, but since #3116 was merged there
are no violations of these rules in the code anymore. Tighten up the rules to
prevent those kinds of errors from creeping back in.
Test Plan:
Lint executes without finding any errors
```
$ ./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.
```
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.
