Add BF Required to Test Builds

Previously, the environment variable that ensures all message creators have
a `BeanFactory` required setting the `SI_FATAL_WHEN_NO_BEANFACTORY` environment
variable to `true`.

Add this variable to `build.gradle`, enforcing the test for all builds.


__Once merged, we can remove the env. variable from the CI build(s)__
Thanks , Gary. There haven't been reason to explain for the purpose of this var.

OK. If guys feel comfortable to specify it for each SI-aware project it won't hurt to commit it to the master.

Will be merged tomorrow.