Convert --setattr values for attributes marked no_update

Attribute Patrams marked no_update never get cloned to Update commands,
and thus never receive the `attribute` flag. This makes their `encode`
method a no-op, which meant they don't get properly encoded when used
with --setattr, making the --setattr fail.

Introduce a `force` argument to encode, which overrides checking
for the attribute flag. Use this in set/add/delattr normalization,
where we know we are dealing with attributes.

https://fedorahosted.org/freeipa/ticket/2616

tests/test_xmlrpc/test_attr.py

@@ -433,7 +433,7 @@ class test_attr(Declarative):
             command=(
                 'user_mod', [user1], dict(
                     addattr=u'nsaccountlock=FaLsE',
-                    delattr=u'nsaccountlock=True')
+                    delattr=u'nsaccountlock=TRUE')
             ),
             expected=dict(
                 result=dict(

tests/test_xmlrpc/test_hbac_plugin.py

@@ -430,6 +430,27 @@ class test_hbac(XMLRPC_test):
          # FIXME: Should this be 'enabled' or 'TRUE'?
         assert_attr_equal(entry, 'ipaenabledflag', 'TRUE')
 
+    def test_ea_hbacrule_disable_setattr(self):
+        """
+        Test disabling HBAC rule using setattr
+        """
+        command_result = api.Command['hbacrule_mod'](
+            self.rule_name, setattr=u'ipaenabledflag=false')
+        assert command_result['result']['ipaenabledflag'] == (u'FALSE',)
+        entry = api.Command['hbacrule_show'](self.rule_name)['result']
+        assert_attr_equal(entry, 'ipaenabledflag', 'FALSE')
+
+    def test_eb_hbacrule_enable_setattr(self):
+        """
+        Test enabling HBAC rule using setattr
+        """
+        command_result = api.Command['hbacrule_mod'](
+            self.rule_name, setattr=u'ipaenabledflag=1')
+        assert command_result['result']['ipaenabledflag'] == (u'TRUE',)
+        # check it's really enabled
+        entry = api.Command['hbacrule_show'](self.rule_name)['result']
+        assert_attr_equal(entry, 'ipaenabledflag', 'TRUE')
+
     @raises(errors.MutuallyExclusiveError)
     def test_f_hbacrule_exclusiveuser(self):
         """