Adds basic support for CNAME files

- Checks for a CNAME file before generating a domain
- Only supports one CNAME (will only be deployed to the first domain
listed)
- Doesn’t assume it’s a Surge subdomain (ex. If you list `example`, it
will try and deploy to `example`, not `example.surge.sh`. I don’t think
this is a good thing, but didn’t add it yet.)
Removes pkg (unnecessary), and fixes quotes
Removes pkg (unnecessary), and d08fda9 didn’t
Uses domain function instead of log helper
Merge pull request #18 from kennethormandy/ko-cname

Adds basic support for CNAME files