Remove the polygon type combobox header

Removed the wrapping panel and push the combo into a panel wrapping it
and the SpatialConstraintDisplayPanel
Merge branch 'master' into remove-polygon-dropdown-header

Conflicts:
	web-app/js/portal/filter/BoundingBoxFilterPanel.js
Merge pull request #712 from aodn/remove-polygon-dropdown-header

Remove the polygon type combobox header