Add Neutron chapter to API reference page

All wadls and samples were there, just needed to modify the
api-ref.xml file to show new sections. Also replaced 'quantum'
instances with 'neutron'.
Builds OK locally.
patchset 4 - diane fleming - fixed merge conflict in api-ref.xml

Fixes bug 1200718

Change-Id: I2840aa69d85e515689346cbf43423723850fe96f