Use git ls-remote instead of "remote -v" to discover repo URL.

"ls-remote" is built for this purpose and is fast too. Avoid looping
and some regex foo to parse it from "remote -v" results.
fix RemoteUrlCommand to work for non .com repo URLs (.net, .org)
Multiple fixes for discovering repo url for non .com repos.

+ Need to chomp the last \n from `git ls-remote`
+ Not all GH enterprise repos support https. Use http and GH will
  automatically rewrite to https as needed
+ Need to replace the tld: correctly.
Don't rely on tlds to discover private GH repos.
Merge pull request #49 from arnab/better-remote-url

Allow RemoteUrlCommand based commands to work with non .com private repos