Proposed new Util.isInitFailed()

Salut Ceki, ça fait un bout, ça va?

I'd like to propose adding an Util.isInitFailed(). This could then be used in an assertFalse("SLF4J Initialization failed", Util.isInitFailed()); kind of check in a @Test, in order to ensure that http://www.slf4j.org/codes.html#multiple_bindings and similar types of errors are caught by an automated test, and then when such problems are fixed other people don't accidentally re-introduce them by adding some new dependency.

The alternative is "watching out" for SLF4J msgs on System.err, which is doable, but in a JUnit TestRule using @Rule or @ClassRule à la something like http://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#boot-features-output-capture-test-utility it's difficult, because this typically happens very early.

PS: The idea for a test like this is for a "product", in this case Mifos the opensource Microfinance platform (which makes a conscious choice of a logger implementation), not for a "framework" library which does not.