doc: add Hacking.md

This guide contains instructions on how to set up a basic development
environment for ZeroCloud using a virtual machine and DevStack.
README: add links to the detailed docs
Merge pull request #20 from larsbutler/hacking-guide

Add ZeroCloud "hacking" guide
Merge pull request #21 from pkit/minor_fixes

add isinstance check to ObjPath equals operator
Merge pull request #22 from pkit/minor_fixes

moved static macros definition from func to module
PEP8: formatting changes, minor comment fixes