Replicated and improved libprocess specific gtest and gmock features
from Mesos into libprocess.

Review: https://reviews.apache.org/r/10175

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1462663 13f79535-47bb-0310-9956-ffa450edef68
Replaced use of libprocess specific gtest and gmock features.

Review: https://reviews.apache.org/r/10176

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1462664 13f79535-47bb-0310-9956-ffa450edef68
Simplified variadic 'delay' implementation.

Review: https://reviews.apache.org/r/10177

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1462665 13f79535-47bb-0310-9956-ffa450edef68
Added EXPECT_DISPATCH.

Review: https://reviews.apache.org/r/10178

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1462666 13f79535-47bb-0310-9956-ffa450edef68
Refactored garbage collector tests to use EXPECT_DISPATCH instead of
sleep.

Review: https://reviews.apache.org/r/10179

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1462667 13f79535-47bb-0310-9956-ffa450edef68