Bug 978639 - Part 1: Add hangUp method (webidl). r=hsinyi
Bug 978639 - Part 2: Add hangUp method (dom). r=hsinyi
Bug 978639 - Part 3: Add hangUpConference method (internal interface). r=hsinyi
Bug 978639 - Part 4: Add hangUpConference method (ipc). r=hsinyi
Bug 978639 - Part 5: Add hangUpConference method (ril). r=hsinyi
Bug 978639 - Part 6: Add test case. r=hsinyi