Improve error message when InjectionManagerFactory is missing

[cowwoc]

Users are thrown off by the fact that they now have to explicitly include a dependency injection implementation. See https://stackoverflow.com/a/44546979/14731

Instead of the exception message stating "InjectionManagerFactory not found` please inform the user how to resolve this problem. For example, point them at a documentation page that explains what options they have and (for example) how to resolve it by including the HK2 implementation.