<ticket>#689</ticket>
<ticket>#689</ticket>

gui/mashups/mashup_app.py:
- QMashupAppMainWindow.__init__:
  Added missing check for sequenceOption is None

Nikea/VisTrails,celiafish/VisTrails,Nikea/VisTrails,hjanime/VisTrails,minesense/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,hjanime/VisTrails,minesense/VisTrails,VisTrails/VisTrails,minesense/VisTrails,Nikea/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,Nikea/VisTrails,hjanime/VisTrails,hjanime/VisTrails,celiafish/VisTrails,minesense/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,VisTrails/VisTrails