The room id can now be a string

this changed in this commit:
https://github.com/github/janky/commit/a438e1f338cc9fecf0775468a669ed13b6356730

We need it to have janky post from hubot into our kato room
Since the room id is now a string, it cannot be zero

But we can check if it is empty instead to use the fallback
Merge pull request #206 from Reprazent/master

handle strings as room_id everywhere