Revised base Action class implementation
Revised base Action class implementation

Major revisions include:
- Made 'signal' an instance method;
- Moved signal checking logic to the Action class;
- Added definition of COMMANDS (SIGNALS is better?)
- Moved timeout checking here to the base class.

tengqm/senlin,tengqm/senlin,tengqm/senlin-container,tengqm/senlin-container,openstack/senlin,openstack/senlin,stackforge/senlin,stackforge/senlin,Alzon/senlin,Alzon/senlin,openstack/senlin