cruise-control-client should accept Python booleans when adding 'json' parameter

[mgrubent]

Background

cruise-control-client allows for users to specify the parameter=value pairs for the endpoint.

For parameters that cruise-control-client has implemented (like json, under JSONParameter), cruise-control-client performs additional verification to ensure that common invalid values are not passed to this parameter.

A valid way to add the json=True pairing should be

endpoint.add_param(parameter_name="json", value=True)

Issue

cruise-control-client falsely invalidates the above, with

    raise ValueError("url must contain the \"json=true\" parameter")

This failure also exists when using an uppercased string rather than a boolean

endpoint.add_param(parameter_name="json", value='True')

Both of the above are incorrect failures, and should be fixed.

A workaround in the meantime is to use a lowercased string

endpoint.add_param(parameter_name="json", value='true')