Separate VF templates for vFW

- Create a new set of Heat templates for the vFW:
  - One base template with the definition of common resources
  - Three add-on modules (VF modules) that describe vFW, vPacketGen, and vSink
  - Examples of env files in the examples directory

For Casablanca, this new template structure will be used for testing CDS capabilities.

Change-Id: Ic6c555074490d9d78f90cb347bc56a01a397ca06
Issue-ID: INT-659
Signed-off-by: Marco Platania <platania@research.att.com>