Body parameters are now handled correctly.

Fixed a bug that caused body parameters to not be sent correctly through
swagger.js due to its inability to deal with body parameters
automatically.

fixes #1
swagger.js expects {body: '{"variables": {"var": "value"}}'}. ARI expects the variables themselves to be wrapped in an object with variables as the key.

This code ensures that we wrap the variables in that object, but only if the user option did not already do so.

In other words, a user, looking at our swagger generated documentation might see that the parameter name is called variables, and that the example for this parameter shows the variables being wrapped in a variables object, and so would construct their options as:

{variables: {variables: {key: 'value'}}}. That is why we check to see if options.variables.variables exists. Otherwise we would wrap it in yet another variables object for users who interpret our documentation correctly.