If the project comes from another git repository you should probably just include that as a submodule. There are rare examples where you would want put it in another repository without forking. Converting a folder from vendor/plugins into a its own project would be one of those rare occasions. First you have to clone original project, then you can extract files without the .git metadata running:
git archive master | tar -x -C /path/to/another/folder
For applications, delete plugin folder for plugins hosted at github, to later add as submodules:
After adding all plugins then you need to commit to local repository:
git commit -m "Adding plugins as submodules."
Request that github repository be created under thl, by simply sending an e-mail to me, amontano@virginia.edu. I would create repos and make you a collaborator.