Do not return error if removing bind mount fails.

Review: https://reviews.apache.org/r/28339
Set memory::limit_in_bytes first, even with limitSwap enabled.

Review: https://reviews.apache.org/r/28305
Changed RunTaskWithCommandInfoWithUser to not use shell.

The 'nobody' user is restricted on some systems from shell access and
broke the task.user tests (which have been disabled since then).  With
the command.shell field, the test can run the command directly.

Review: https://reviews.apache.org/r/26894
Allow mesos containerizer to destroy correctly at each state.

Review: https://reviews.apache.org/r/28141
Fix style issue for mesos containerizer commit.
Allowed slave to checkpoint resources.

Review: https://reviews.apache.org/r/26990
Fixed a compilation error on gcc-4.4.

Review: https://reviews.apache.org/r/28357