Add Check for Local Paths in Gemfile

This checks your Gemfile to make sure that no local paths were inadvertently left in.  This is a warning check only since I consider it good practice to create gems in your `lib` directory which breaks up the functionality in your application.  In those cases it's desirable to have local paths in your Gemfile, but it's also the case the local paths are used for debugging gems and working with local copies of gems you're developing outside the application.  In these cases committing a local path would not be good.

Submitted to the academy for their approval. :smile: