Coerce the contents of unquote-splice'd things to a list

This fixes the conversion issue in the following macro:

(defmacro doodle [&rest body]
  `(do ~@body))
Add test for unquote-splice behavior
Always import __future__.print_statement in hy code

This allows us to drop the print special-casing in the
compiler, and makes behavior consistent in Python2/3.
Merge pull request #297 from olasd/print-function

Always import __future__.print_statement in hy code
Merge pullrequest #296