Add grammar rule for one-line anon fns. Refs #59

Unfortunately this fix also broke a couple other tests around multi-line anon fns.
Move grammar rules around.

This alleviated a precedence error I was getting:
  .do < else:. < .do
Add logic to handle indenting anon fns. Refs #59
Merge pull request #63 from elixir-lang/indent-anon-fns

Correctly indent one-line anon fns AND block fns. Fixes #59