get_driver requires Provider lookup not just region

[Chris Ferry]

Passing only region to get_driver in module.py:85
self.cons.append(get_driver(region)(self.api_key, self.secret))

fails with latest libcloud(0.16.0)
[1422474614] ERROR: [Shinken] The instance aws-import raised an exception Provider ec2_us_east does not exist, I remove it!

Need to look up region as an attribute on Provider.

[veurits]

The #11 didn't fix my issue , I changed it in #15 , hope this will work for more people.

Rgds,
Veurits