Add HACKING.rst
Add HACKING.rst

This document now refers to OpenStack style commandments which can be
extended later based on project requirements.

Change-Id: Iee51fea153325308dcd3240f1df17a0e248fd9d1

ed-/solum,openstack/solum,ed-/solum,mohitsethi/solum,gilbertpilz/solum,julienvey/solum,ed-/solum,stackforge/solum,mohitsethi/solum,stackforge/solum,gilbertpilz/solum,openstack/solum,devdattakulkarni/test-solum,gilbertpilz/solum,gilbertpilz/solum,devdattakulkarni/test-solum,julienvey/solum,ed-/solum