-Fixing the submodules path to a public repo URL

The submodules command fails because the url you guys have used for tests repo only works if you have the write access to tests repo. The fix is to use a public Github repo url.

http://stackoverflow.com/questions/8197089/fatal-error-when-updating-submodule-using-git

In addition to that I added the missing step in README.md which is required for successful compilation of the project