Added a more comprehensive slave recovery test to confirm that the
restarted slave can communicate with scheduler, executor and master.

Review: https://reviews.apache.org/r/9992

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1459092 13f79535-47bb-0310-9956-ffa450edef68
Added registration timeout for executors.

Review: https://reviews.apache.org/r/8077

git-svn-id: https://svn.apache.org/repos/asf/incubator/mesos/trunk@1459093 13f79535-47bb-0310-9956-ffa450edef68