smoke-tests should be a part of the top-level project, not separated

At the moment, smoke-tests aren't really a subroject of bigtop, as they have their own settings.gradle and are suppose to be executed from their own build.gradle

I propose we actually hook them up to the top level project, so all smokes will be visible when gradle projects is ran. This also will supposedly simplify current requirements like a need to have BIGTOP_HOME, ITEST, -Dsmoke.tests, etc. Instead, test could be run like this (from the top-level directory):

gradle bigtop-tests:smoke-tests:mapreduce:test

or, perhaps to run all of them

gradle bigtop-tests:smoke-tests:test

Thoughts?