Wait for process spec file to get actually copied
Wait for process spec file to get actually copied

The runtime plugin runs in parallel. Therefore it may happen that the
fake runtime plugin has created the empty file but not to have written
it yet.

[#153696780]

Signed-off-by: Julia Nedialkova <7434cf6db6c17ad5b6ef614abe065a9cda1d30c1@hotmail.com>

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