Refactored allocator tests to use Triggers and the -Call convention.
Also removes the code for checkResources which was removed from use in
a previous patch.

From: Thomas Marshall <twm378@gmail.com>
Review: https://reviews.apache.org/r/9407

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1462822 13f79535-47bb-0310-9956-ffa450edef68