Add support for specificing `force_config_drive` in nova.conf.
Update README.md to include options for `force_config_drive`.
Merge branch 'grizzly' of git://github.com/rcbops-cookbooks/nova into grizzly

Conflicts:
	templates/default/nova.conf.erb
Merge pull request #281 from byronmccollum/grizzly

Add support for specifying `force_config_drive` in nova.conf.