Implement Cloudant.bluemix client class method

[smithsz]

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What

Implement Cloudant.bluemix() client class method.

Example Usage

import os
from cloudant.client import Cloudant

c = Cloudant.bluemix(os.getenv('VCAP_SERVICES'), 'Cloudant NoSQL DB')

Testing

Includes additional unit tests.

Issues

Fixes #313.

[emlaver]

I think it would be good to test with a JSON object that has multiple Cloudant instances to verify that instance_name is working correctly.

[smithsz]

Good thinking. I'll add an additional test. I'll also add a test for 1 service in VCAP without specifying instance_name.

tests/unit/cloud_foundry_tests.py is testing majority of this. But since I've already gaffed this once it'd be good to test again at the client instantiation level too.

[ricellis]

+1 just the CHANGES comment needs a tweak I think.

[ricellis]

I'm not sure a "Cloudant Bluemix client" is really a thing.
Instantiating a client from VCAP_SERVICES metadata?
Last time we went with:

• [NEW] Added cloudant_bluemix method to the Cloudant client allowing service credentials to be passed using the CloudFoundry VCAP_SERVICES environment variable.

[ricellis]

Copyright date on this file is a bit weird, but I think it's fixed in #306 anyway.