Add method createOfferOptions

[ekzobrain]

It would be great to add a new polyfill to handle differences in createOffer options dict. Firefox already supports (from version 33-34) a new syntax http://www.w3.org/TR/webrtc/#idl-def-RTCOfferOptions (and throws deprecation warning when using "mandatory: {}"). Googgle Chrome still doesn't accept new syntax, I did not yet check the plugin. To fix this I use this helper function. I think it's place is in AdapterJS library :)

/**
* Create options dict for RTCPeerConnection.createOffer()
* @see http://www.w3.org/TR/webrtc/#idl-def-RTCOfferOptions for param description
* 
* @param recieveAudio
* @param recieveVideo
* @param iceRestart
* @param voiceDetection
* 
* @returns {Object}
*/
function createOfferOptions(recieveAudio, recieveVideo, iceRestart, voiceDetection) {
    var options;

    iceRestart = iceRestart || false;
    voiceDetection = voiceDetection === false ? false : true;

    // current spec: http://www.w3.org/TR/webrtc/#idl-def-RTCOfferOptions
    if (webrtcDetectedBrowser === 'firefox' && webrtcDetectedVersion >= 36) {
        options = {
            offerToReceiveAudio:    recieveAudio,
            offerToReceiveVideo:    recieveVideo,
            iceRestart:             iceRestart,
            voiceActivityDetection: voiceDetection
        };
    }

    // old spec: http://www.w3.org/TR/2013/WD-webrtc-20130910/#constraints
    else {
        options = {mandatory: {
            OfferToReceiveAudio:    (recieveAudio ? true : false),
            OfferToReceiveVideo:    (recieveVideo ? true : false),
            IceRestart:             iceRestart,
            VoiceActivityDetection: voiceDetection
        }};
    }

    return options;
}

[serrynaimo]

Cool. Gonna review and evaluate!