Remove the yarn link approach from importing browse-everything-react into .internal_test_app

[jrgriffiniii]

The approach should instead automate the following tasks:

export BE_REACT_BRANCH=master # Or, some other branch
export BE_REACT_URL=https://github.com/samvera-labs/browse-everything-redux-react.git  # Or, some fork
cd .internal_test_app/node_modules
rm -fr browse-everything-react
git clone -b $BE_REACT_BRANCH $BE_REACT_URL
cd ../..
ln -s .internal_test_app/node_modules/browse-everything-react

This seems to be the only stable way of offering an integrated development environment. The documentation will obviously need to be updated with this as well.