0.1.0-alpha010

Added two new HttpHandler functions:

• negotiate checks the Accept header of a request and determines automatically if a response should be sent in JSON or XML
• negotiateWith is the same as negotiate, but additionally accepts an IDictionary<string, obj -> HttpHandler> which allows users to extend the default negotiation rules (e.g. change default serialization if a client is indifferent, or add more supported mime types, etc.)