ShellCommandPage: Disable/enable back button
ShellCommandPage: Disable/enable back button

Change-Id: I19bed185ea89d47871efd07b34cc99b4739b7659
Reviewed-by: Orgad Shaneh <2b010cbad792a0c0a8175f752f93f83941fc6bc1@gmail.com>

xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,xianian/qt-creator