Use python2 in Python script shebang lines

This fixes issue #3336.

poller-service.py

@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python2
 """
  poller-service A service to wrap SNMP polling.  It will poll up to $threads devices at a time, and will not re-poll
                 devices that have been polled within the last $poll_frequency seconds. It will prioritize devices based

poller-wrapper.py

@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python2
 """
  poller-wrapper A small tool which wraps around the poller and tries to
                 guide the polling process with a more modern approach with a

scripts/agent-local/nginx

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 import urllib2
 import re
 

scripts/mysql-stats

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 import warnings
 import re
 warnings.filterwarnings(action="ignore", message='the sets module is deprecated')

scripts/nginx-stats

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 import urllib2
 import re