kmswebrtendpoint: add KmsWebRTCConnection and KmsWebRTCTransport
kmswebrtendpoint: add KmsWebRTCConnection and KmsWebRTCTransport

This abstractions help us to manage WebRTC ICE-DTLS-SRTP connections.

Change-Id: I86ada295a26e7229354238e52f3356f96fcc3a4c

Kurento/kms-core,Kurento/kms-core,TribeMedia/kms-core,ESTOS/kms-core,shelsonjava/kms-core,KurentoLegacy/gst-kurento-plugins,Kurento/kms-core,TribeMedia/kms-core,KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins,KurentoLegacy/gst-kurento-plugins,shelsonjava/kms-core,Kurento/kms-core,TribeMedia/kms-core,TribeMedia/kms-core,ESTOS/kms-core,shelsonjava/kms-core,shelsonjava/kms-core,ESTOS/kms-core,ESTOS/kms-core