Fix soc.views.site.EditSitePage.validate to return True or False.
Fix soc.views.site.EditSitePage.validate to return True or False.

Previously it returned False or None (which would be interpreted
by callers as False). This defect appears to have been introduced
in revision a28054f4304232e8dd130615d2131c6c5a96cdb4.

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son