sumbols-like strings

Hi there! I've seen issues about symbol-like strings. But still haven't understood why don't you like this. Sure, it's not good idea to replace symbols with numbers, but i think it's good enough as shortcut in some cases. Like this
```coffee
$.ajax
  type: :json
  data:
    val:        :smth
    other_val:  :smth_else
#instead of
$.ajax
  type: 'json'
  data:
    val:        'smth'
    other_val:  'smth_else'
```
I've implemented this feature, it has taken just few lines and hasn't broken anything :)

Hope you'll like it!