Introduced the VariableControl, which will be used in role(s),

database(s), and tablespace(s).

Thanks Harshal Dhumal for sharing the original patch.

I've modified a lot to work by fetching the variables later by giving a
url.

Also,
- Introduced the template macros for SECURITY LABELS and VARIABLES.
- Improvised the Backform.Control with better syntactic approach.
- Introduced a jquery function pgMakeVisible(..) to make it visible
  under any obj which can be identified by unique class.

web/pgadmin/browser/server_groups/servers/__init__.py

@@ -97,6 +97,11 @@ class ServerModule(sg.ServerGroupPluginModule):
             'name': 'pgadmin.browser.server.privilege',
             'path': url_for('browser.index') + 'server/static/js/privilege',
             'when': self.node_type
+            },
+            {
+            'name': 'pgadmin.browser.server.variable',
+            'path': url_for('browser.index') + 'server/static/js/variable',
+            'when': self.node_type
             }])
 
         for module in self.submodules: