This reverts commit e2c9fee8ed846aba124a2fc1bba245790ed7ba90.
We have decided that we don't want to support the json-style argument
as described by bug#1374118 (see thread at [1]).
This restores the old behavior of sending the argument in
double-quotes so environment variables get expanded. As a bonus,
tests for this are added.
[1] http://lists.openstack.org/pipermail/openstack-dev/2014-October/049341.html
Change-Id: I9fc99f3716cc53366907878adb00ae6cf3898f14
Closes-Bug:#1386413