Fix #164. Initialize 'registrator' in the 'UA' constructor. Thanks @nilsonfreitas

- registrator is an internal UA element which must be initializated in the constructor
Fix #148: WebSocket reconnection behaviour
Fix #176. Update to the latest IceServer definition

Old:

dictionary RTCIceServer {
    DOMString  url;
    DOMString? credential;
};

New:

dictionary RTCIceServer {
    (DOMString or sequence<DOMString>) urls;
    DOMString?                         username = null;
    DOMString?                         credential;
};

Note: Current Firefox Nightly "28.0a1 (2013-11-18)" Does not support multiple 'urls'
Fix typo in Gruntfile.js

InDialogRequestSender.js is now located under /src/Dialog
Fix #150. Avoid possible UUID prefix duplication. Thanks @gavllew
Fix #139. Replace deprecated 'onicechange' method with 'oniceconnectionstatechange'
New 'mediaStream' argument for UA.call() and RTCSession.answer()

Allows indicating a mediaStream when calling or answering a call
in order to avoid calling getUserMedia everytime.
Allow passing an empty array as a configuration parameter.
Allow incoming MESSAGE with Content-Type other that text/plain and text/html (don't live in the past).
Set local_identity and remote_identity properly in JsSIP.Message
Reply incoming INVITE with '405' in absence of 'newRTCSession' event handers
add 'getHeader', 'getHeaders' and 'hasHeader' methods to JsSIP.OutgoingRequest
Bugfix. Enable setting the log level by the corresponding String ('error, warn, log, debug')
RTP Timeout handling

Terminate RTCSession when iceConnectionState turns to 'disconnected'
Fix #127. Make in dialog requests atomic. Thanks @gavllew
Fix #102. Enhance RFC3261 Section 15 (Terminating a Session)

...the callee's UA MUST NOT send a BYE on a confirmed dialog
until it has received an ACK for its 2xx response or until the server
transaction times out...
Fix #85. Do not add ';ob' in Contact of inital INVITE if we got a GRUU URI

RFC 5626 Section 4.3 "Sending Non-REGISTER Requests":

"If the UAC is using a Globally
Routable UA URI (GRUU) [RFC5627] that was instantiated using a
Contact header field value that included an "ob" parameter, the UAC
sends the request over the flow used for registration, and subsequent
requests will arrive over that same flow.  If the UAC is not using
such a GRUU, then the UAC adds an "ob" parameter to its Contact
header field value."
Fix #128. Retransmitted 2XX may not match the original one. Thanks @gavllew

Retransmitted 2XX didn't include the extra headers included in the original one.
Fix #114. Handle 2XX responses from forked INVITEs. Thanks @gavllew
Fix #84. Enhance 'Supported' header field setting