Adding openstack-omnibus attributes

Developing an attribute framework for enabling and disabling omnibus
services. Users can override the portions they would like to change.
For the time being, this will support Ubuntu only.
Add a recipe that sets upstream attributes

This recipe should be included early in the node's runlist. Doing so
it will perform a number of node attributes in order to change the
functionality of the subsequent upstream cookbooks.
Adding upstart script template and recipe

This recipe configures upstart for the services enabled in the node's
attributes. For right now, we will support upstart only, but other
service management mechanisms may be developed later.
Add a default recipe

The default recipe calls node_attributes and upstart_services. This
will eventually support other configuration combinations.
Add metadata for cookbook

Initial commit of metadata.