Always use source origin, and then add fork as username

Fixes #5, and acts like hub command.

Forking dgtized/github-clone.el will result in that as origin, and
optionally add a local fork with your github username.
Remove unnecessary upstream detection, clone origin and optionally fork
Don't attempt to fork repo if user already owns it
Fix error in format string
Update web documentation to match new clone and fork behavior
Release version 0.2 using the new clone and optionally fork style
Merge pull request #6 from dgtized/use-hub-style-clones

Use hub style clones