Refactoring try_install_all to take an optional list of engines to test.
Refactoring try_install_all to take an optional list of engines to test.

bendmorris/retriever,bendmorris/retriever,davharris/retriever,henrykironde/deletedret,davharris/retriever,embaldridge/retriever,goelakash/retriever,embaldridge/retriever,goelakash/retriever,embaldridge/retriever,bendmorris/retriever,henrykironde/deletedret,davharris/retriever