Quote repo var for apt repo's other than ppa's

The repo option should be quoted as noted in the docs: http://docs.ansible.com/apt_repository_module.html.

I had issues using the default ppa(not able to validate the SSL cert) and had to use the deb source URL instead.
Merge pull request #1 from nickhammond/patch-1

Quote repo var for apt repo's other than ppa's