disable rule in individual file

[curtiszjohn]

I know that we can disable a rule but we are looking to disable a rule for only a few files, ex: no-css-comments. We utilize a living style guide generator that depends on the multiline comments in the sass file.

Linter would look for the following while reading sass files:
// sass-lint: disable <rule name>

[DanPurdy]

Please follow #402