git clone git@github.com:whatever folder-name
git clone https://github.com/sferik/sign-in-with-twitter.git signin
git clone URLofRepo .
git clone [repo]
cd [name of sub-dir]
git filter-branch --prune-empty --subdirectory-filter [path to sub-dir] HEAD
With same Git Repository name
git clone git@github.com:whatever folder-name
With Different Git Repository name
git clone https://github.com/sferik/sign-in-with-twitter.git signin