Parameter constraint samples for HOT hello world

Adding example for parameter validation constraints to HOT hello world
template to show new syntax and features for parameter constraints in
HOT.

This change depends on changes in the heat github repository, which
need to be completed so this new template can be processed.

Contributes to blueprint hot-parameters

Change-Id: I720f22795c94e4ceacc9ebe030929f9b58e981e9