feat/Sanitise resource names to ensure they are valid Python identifiers

[jakul]

Clean resource names to ensure they:

• can be used as valid Python identifiers, and
• match the naming style guide for the operation sanitisation

This is a breaking change, becuase resources which are currently called My Tag will now be called My_Tag. For users of bravado it will mean workarounds like getattr(client, 'My Tag').api_method().result() will need to be replaced with client.My_Tag.api_method().result(). I'm not sure what the impact of that change will be on any other libraries which depend on bravado-core.

Fixes Yelp/bravado#307. I have also proposed a different fix for the same problem in Yelp/bravado#320. I'm not sure if it's better to fix this in bravado-core or bravado (or both).

[coveralls]

Coverage increased (+0.01%) to 98.001% when pulling 690bcbb on jakul:feat/sanitise-tags-with-spaces into 249c602 on Yelp:master.

[soumyakantiroychowdhury]

I also faced this issue and bypassed it using getattr(client, 'My Tag').api_method().result(). I am not in favor of your proposed change to rename My Tag to My_Tag internally, if it breaks the existing code after upgrade.

Is it possible to do something like this:
self.client.Resource('My Tag').api_method().result()?

[sjaensch]

Two comments:

1. The bravado SwaggerClient class already has a method _get_resource, you can use it to fetch a resource with special characters. The underscore is just there to avoid name clashes, it's a public method.
2. This change is not backwards-compatible. It breaks existing code that uses _get_resource or the getattr trick mentioned by @soumyakantiroychowdhury to retrieve the resource.

I've tried a different approach in #243 that also sanitizes param names, let me know what you think.