Fix crash when launching an EC2 instance.

Fixes the following exception when trying to launch an EC2 instance via salt-cloud:

```
[INFO    ] Salt installed on test
[ERROR   ] There was a profile error: 'Node' object is not iterable
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/salt/cloud/cli.py", line 331, in run
    self.config.get('names')
  File "/usr/local/lib/python2.7/dist-packages/salt/cloud/__init__.py", line 942, in run_profile
    ret[name] = self.create(vm_)
  File "/usr/local/lib/python2.7/dist-packages/salt/cloud/__init__.py", line 856, in create
    output = self.clouds[func](vm_)
  File "/usr/local/lib/python2.7/dist-packages/salt/cloud/clouds/libcloud_aws.py", line 515, in create
    ret.update(data)
TypeError: 'Node' object is not iterable
```