Muda setting para ?iframe=0 (desativa) e ?iframe=1 (ativa)

Fixes #1189

sapl/base/templatetags/common_tags.py

@@ -119,13 +119,19 @@ def str2intabs(value):
 
 @register.filter
 def has_iframe(request):
+
     iframe = request.session.get('iframe', False)
     if not iframe and 'iframe' in request.GET:
+        ival = request.GET['iframe']
+        if ival and int(ival) == 1:
             request.session['iframe'] = True
             return True
-    if 'no-iframe' in request.GET and iframe:
+    elif 'iframe' in request.GET:
+        ival = request.GET['iframe']
+        if ival and int(ival) == 0:
             del request.session['iframe']
             return False
+
     return iframe