qmlavplayer: mimic qtmultimedia's mediaObject

signal connections are moved in beginClass() as in qtdeclarativeaudio
(MediaPlayer)
Merge pull request #294 from sherpya/master

mimic qtmultimedia's mediaObject
simplify stop logic.
qml: do not call stop after setSource

if autoPlay is true, setSource will call play
workaround for qml crash on startup
deb: add players
repackaging for deepin