support editMessage and removeMessage

[demurgos]

Reference: https://github.com/ShyykoSerhiy/skyweb/issues/19

• URI: https://{host}/v1/users/{user}/conversations/{conversationId}/messages
• Body:

{
    content: editedContent // empty string to remove
    contenttype: "text"
    messagetype: "RichText"
    skypeeditedid: "4059726727402763698" // clientmessageid
}