Change openai engine to gpt-3.5-turbo and a few other enhancements

[PiratedKukreja]

Try changing the Completion engine from text-davinci-003 to ChatCompletion engine gpt-3.5-turbo. Pros of gpt-3.5 over davinci are the cost and the quality of response, 3.5 turbo's cost is similar to that of text-curie which is lower than text-davinci but responses are similar if not better than davinci. Another enhancement can be to allow the user to select the count of words under which the text should be summarised, passing that number in the prompt will help generate a user specific response. ++ setting response-type to stream can help users get real time synthesised result in their console :)