Add LimitCpuRequest to warden protocol

[#62173454]

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Dispatch LimitCpuRequest

Configure cgroup cpu.shares to set cpu limit for a container.

[#62173454]

Signed-off-by: Eric Malm <emalm@pivotallabs.com>
Revert "Increase niceness of warden containers by 10"

This reverts commit 7a47c4bf7317b4d1c24f3be449d1cb08a600a4d0.

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Add Trusty to supported releases of setup_fs_ubuntu

Signed-off-by: Casey McTaggart <cmctaggart@pivotallabs.com>