Fix some colon parsing issues and add multi-line string support

This fixes a couple of issues related to colon parsing.
It now handles things of the form
name  :  value

It also doesn't split on
name:foo
since a space is needed after the colon

I think this encompasses the changes from https://github.com/kylelemons/go-gypsy/pull/10 and will conflict.

Also handled https://github.com/kylelemons/go-gypsy/issues/1, which I needed.