Support settings options for Coffeelint

I use `b:ale_javascript_eslint_options` to set a custom eslint file location, so I thought I would be able to do that with _all_ the linters, but after tediously parsing through code to understand what's happening, I see that `ale_linters#coffee#coffeelint#GetCommand` doesn't use `ale#Var` the way that the eslint linter does. Specifically, I'm looking to add `-f ~/.coffeelint.json` because I hate the max_line_length error. Is that something you'd be open to getting a pull request for? (I've had a similar issue with `stylelint`). Relatedly, is there a particular reason some of the linters define a `GetCommand` inside the same file (e.g. `ale_linters/coffee/coffeelint.vim`) whereas others define one in `autoload/ale/handlers/` (e.g. `autoload/ale/handlers/eslint.vim`)?