Explicitly set mount options on /dev/shm
Explicitly set mount options on /dev/shm

On xenial stemcells /dev/shm is not mounted with nodev by default, but
it is in trusty. Explicitly set options to avoid the discrepancy.

[#154140049]

Signed-off-by: Ed King <cb0ef010d3b7764b76e01d19f7526ae755120a2b@pivotal.io>

cloudfoundry-incubator/guardian,cloudfoundry-incubator/guardian,cloudfoundry-incubator/guardian