Delete conversation

[scmanjarrez]

I've seen that removing a chat in Edge generate a POST in https://sydney.bing.com/sydney/DeleteSingleConversation with the following data

{"conversationId":"51D|BingProd|5E9A0DF8EDE9DE3XXXXXX7EE26B3D36A259BDBDC7802BC87AE640528E4","conversationSignature":"XXXXXXXXXKrsthLom+6fSBhKjkBMRQeZmxDA=","participant":{"id":"xxxxxx"},"source":"cib","optionsSets":["autosave"]}

I was thinking about doing a PR with the implementation of a delete() or .remove() function to delete the chat.
What do you think? Should we use a separate function for that, or reuse .close() to remove the chat in addition of closing the conversation? Or instead create a similar function that removes the chat and closes the conversation (something like .remove_and_close())?

[scmanjarrez]

Completed in #541