Add network parameters to Heat template creation.

In order to allow the allocation of a floating IP in the heat
template, we need to give network paremeters as input.

This patch :
- updates the heat template to associate a floating IP to the
created server
- Use python-neutronclient to find the needed network id to pass to
the heat template

Fixes bug 1301324

Change-Id: If6182d1bf6196022b77bfaf26d2563a483f1a460
Merge "Add network parameters to Heat template creation."