Revert some changes - functional Ok. Interfaces mess

tests/functional/__init__.py

@@ -7,3 +7,7 @@ sip.setapi(u'QTime', 2)
 sip.setapi(u'QUrl', 2)
 sip.setapi(u'QVariant', 2)
 
+from PyQt4 import QtGui
+
+# Only one QApplication can be created. Use QtGui.QApplication.instance() when you need to "create" a  QApplication.
+application = QtGui.QApplication([])

tests/functional/openlp_core_lib/test_image_manager.py

@@ -20,7 +20,7 @@ class TestImageManager(TestCase):
         Create the UI
         """
         Registry.create()
-        self.app = QtGui.QApplication([])
+        self.app = QtGui.QApplication.instance()
         ScreenList.create(self.app.desktop())
         self.image_manager = ImageManager()
 

tests/functional/openlp_core_lib/test_screen.py

@@ -23,8 +23,8 @@ class TestScreenList(TestCase):
         """
         Set up the components need for all tests.
         """
+        self.application = QtGui.QApplication.instance()
         Registry.create()
-        self.application = QtGui.QApplication([])
         self.application.setOrganizationName(u'OpenLP-tests')
         self.application.setOrganizationDomain(u'openlp.org')
         self.screens = ScreenList.create(self.application.desktop())