<bugfix>Fix BooleanWidget default handling</bugfix> <ticket>#699</ticket>
<bugfix>Fix BooleanWidget default handling</bugfix>
<ticket>#699</ticket>

As long as we set the ConstantWidgetMixin's value to the default, all
of the extra flags are unnecessary.

vistrails/gui/modules/constant_configuration.py:
  - BooleanWidget.__init__: get value from either default or strValue,
    then call setDefault and setContents if values are set
  - BooleanWidget.setContents: don't default value since setDefault
    may have set it
  - BooleanWidget.setDefault: just call setContents

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