Apache cloudstack integration for Stratos

Created two java classes in org.apache.stratos.cloud.controller component.
1. CloudstackPartitionValidator.java - implements PartitionValidator
2. CloudstackIaas.java - Extends Iaas.java

Added cloudstack dependancy to Stratos
Added cloudstack sample configuration to cloud-controller.xml


In general we use log.fatal() in scenarios where the system cannot work due to some reason. Shall we change this to log.error()?