Add a new system hook replacing static button for Performance Test

Ticket:	#5466

gui/system/__init__.py

@@ -24,4 +24,6 @@
 # POSSIBILITY OF SUCH DAMAGE.
 #
 #####################################################################
-
+from freenasUI.freeadmin.apppool import appPool
+from .hook import SystemHook
+appPool.register(SystemHook)

gui/system/hook.py

+from django.core.urlresolvers import reverse
+from django.utils.html import escapejs
+from django.utils.translation import ugettext as _
+
+from freenasUI.freeadmin.hook import AppHook
+
+
+class SystemHook(AppHook):
+
+    name = 'system'
+
+    def hook_form_buttons_AdvancedForm(self, form, action, *args, **kwargs):
+        from freenasUI.middleware.notifier import notifier
+        has_failover = hasattr(notifier, 'failover_status')
+        btns = []
+        if (
+            has_failover and notifier().failover_status in ('MASTER', 'SINGLE')
+            or not has_failover
+        ):
+            btns.append({
+                'name': 'PerfTester',
+                'verbose_name': _('Performance Test'),
+                'onclick': 'editScaryObject(\'%s\', \'%s\');' % (
+                    escapejs(_('Performance Test')),
+                    escapejs(reverse('system_perftest')),
+                ),
+            })
+        return btns