nova/virt/guest-tools/guest_tool.sh as guest_tool.py
can be invoked directly during guest startup.
* Removed 'nova/virt/guest-tools/' and the encompassed script
'guest_tool.py' is moved to 'etc/vmware_guest_tool.py'
* Moved image vmwareapi_blockdiagram.jpg from 'nova/virt/' to
'doc/source/images/' so that it'll be picked up by document build scripts.
* Moved vmwareapi_readme.rst from 'nova/virt/' to
'doc/source/' so that it'll be handled by document build scripts.
* Added 'Introduction' section to 'vmwareapi_readme.rst'
* Added vmwareapi module diagram to readme document. Added reference
to 'images/vmwareapi_blockdiagram.jpg' in document 'vmwareapi_readme.rst'