If using relative SetVolume or SetPosition in rapid succession old info is used

[tjhrulz]

Since I wait for return info from the website to update info it is possible for the old volume to be used if you were to send the command twice within the 50ms update window.

While the simple fix would be to assume that the value will change I think if I want to do that I might as well write every command to assume the info will update and rewrite the javascript to resend info if I assumed wrong (and possibly even if I assumed right). This will mean I can lower the refresh rate on the js side and while there is not any noticeable increase in CPU usage from the plugin it would just be nice.