Major refactor of cloud/service/resource framework

Cloud has a dict of (service name, client object) to select client
Service provides a client via get_client() method
Resource provides discovery of properties via discover() method
TODO(ogelbukh): add docstrings to the code
Sample pump.py script

Discovers resource by type and ID
Add missing services/keystone module
Fix service classes

Remove __init__ method from service classes
Return client instead of client.client in cloud.py module
Remove debug print statements
Fix Tenant resource class

Remove not needed __init__ function from Tenant class
Make Tenant.discover() a proper class method
Remove __init__() from Flavor class
Set Flavor.id property in Flavor.discover() class method
Add Makefile for automation of builds

Add Makefile with 'clean' target to remove all .pyc files from
the repository
[docs] Add docstrings to Cloud class
Fix discovery class method in resource classes

Add __init__() function to resource classes
Make discovery() return instance of class instead of class itself
Add Image to known types of resources
Implement get_client() method in Glance service class
[docs] Fix docstrings in cloud.py module