Adding HOT WordPress_NoKey sample

Adding WordPress_NoKey sample for F18 based on the same
CFN sample.
The HOT sample uses a new function str_replace to simplify the definition
of the instance init script. More cleanup can be done as soon as the
native compute instance resource becomes available.

Note: the new sample depends on change https://review.openstack.org/41461
in the heat github repository for processing the str_replace function.

Change-Id: Idc1986b0cca08d094079b83653967bba14d07a7b