Added additional filter options for instances for EC2 and Eucalyptus

Added the following filter options:

           'ami_launch_index': inst.ami_launch_index,
           'private_ip': inst.private_ip_address,
           'private_dns_name': inst.private_dns_name,
           'dns_name': inst.dns_name,
           'state_code': inst.state_code,
           'architecture': inst.architecture,
           'image_id': inst.image_id,
           'key_name': inst.key_name,
           'virtualization_type': inst.virtualization_type,
           'placement': inst.placement,
           'kernel': inst.kernel,
           'ramdisk': inst.ramdisk,
           'launch_time': inst.launch_time,
           'instance_type': inst.instance_type,
           'root_device_type': inst.root_device_type,
           'root_device_name': inst.root_device_name,
           'state': inst.state,
           'hypervisor': inst.hypervisor

Allows more flexibility when dealing with the ec2 module in plays.