Need to update getStats() to avoid browser warning

[atsakiridis]

Seems that there was an update in the behavior:

non-maplike pc.getStats access is deprecated! See http://w3c.github.io/webrtc-pc/#example for usage.WebRTComm.js:2266
SIPTransactionStack.prototype.removeDialog(): id=74e0fba480d5e74b7fd7a5a916157ac8@10.0.0.5:1477922007598:45534198_97e63ecd_57a5b08a_e0ae10ffjain-sip.js:24198:5
PrivateJainSipClientConnector:processDialogTerminated()WebRTComm.js:1684:2