Do not rely on system bus to catch EOS events.
Do not rely on system bus to catch EOS events.

Use a probe installed in sink element to catch EOS event in the
streaming thread instead of doing it from the main loop.

Change-Id: I7a6b4fba30d733a0e2f91b2e0e8651792cd45beb

Kurento/kms-elements,shelsonjava/kms-elements,Kurento/kms-elements,TribeMedia/kms-elements,shelsonjava/kms-elements,Kurento/kms-elements,TribeMedia/kms-elements,shelsonjava/kms-elements,TribeMedia/kms-elements