Removes qtconnectivity_experimental.bb which is not needed anymore since asteroid-btsyncd is implemented over BlueZ's GATT DBus API

qtbase: enable the glib loop which is needed for example by mlite for DConf watch features (used via nemo-qml-plugin-configuration)

This reverts commit 5027055e.

This reverts commit a8d98acc.

qtbase: enables accessibility which is needed by QtQuick, icu which is needed by QtWebKit and sql-sqlite which is needed by lipstick

qtbase: Forces GLES2 usage because of this issue: https://bugreports.qt.io/browse/QTBUG-46831 it will be solved on Qt 5.6

While we don't have Qt 5.5 in meta-qt5 we must use an older commit of lipstick which depends on deprecated libs like qmsystem2. They should be removed as soon as meta-qt5 will be updated.