Fix exception being thrown for new instance registration with ELB

[mohangk]

Currently if we are trying to register an instance that has not yet
been registered with the elb an exception is thrown as follows:

Traceback (most recent call last):
File "/home/ubuntu/.ansible/tmp/ansible-1388916053.26-72858643329411/ec2_elb", line 1412, in
main()
File "/home/ubuntu/.ansible/tmp/ansible-1388916053.26-72858643329411/ec2_elb", line 335, in main
elb_man.register(wait, enable_availability_zone)
File "/home/ubuntu/.ansible/tmp/ansible-1388916053.26-72858643329411/ec2_elb", line 168, in register
self._await_elb_instance_state(lb, 'InService', initial_state)
File "/home/ubuntu/.ansible/tmp/ansible-1388916053.26-72858643329411/ec2_elb", line 213, in _await_elb_instance_state
if instance_state.state != initial_state.state:
AttributeError: 'NoneType' object has no attribute 'state'

This is expected because the code is querying the elb for the state of the new instance and it responds with a "InvalidInstance" response (as its not been registered with the ELB yet) and the code sets the value of the initial_state to None.

This code change checks if the initial_state is None. If it is, its safe to assume that its state has changed.

[jctanner]

@mohangk I think your patch will work, but I would prefer to prevent the exception by using hasattr() on the object.

[mohangk]

Thanks!