Give the command executor some cpu and memory.

Review: https://reviews.apache.org/r/22251
Wait on Containerizer::update to complete before sending status update.

Review: https://reviews.apache.org/r/22253
Fix some clang compiler issues in perf code.
Minor style fix.
Enabling ZooKeeper tests that were previously disabled.

Review: https://reviews.apache.org/r/22591
MESOS-1312: Added orphan_tasks and unregistered_frameworks in
master's state.json.

Added orphan_tasks and unregistered_frameworks in state.json to display
tasks that are currently running on the slaves, but do not belong to
any already (re-)registered frameworks.

Review: https://reviews.apache.org/r/22223