Add initial neutron API discussion document.
Add initial neutron API discussion document.

TrimBiggs/calico,anortef/calico,Metaswitch/calico,neiljerram/felix,kasisnu/calico,kasisnu/calico,nbartos/calico,TrimBiggs/calico,ocadotechnology/calico,alexhersh/calico,matthewdupre/felix,beddari/calico,ocadotechnology/calico,Metaswitch/calico,neiljerram/felix,nbartos/calico,neiljerram/felix,anortef/calico,alexhersh/calico,neiljerram/felix,matthewdupre/felix,beddari/calico