Add isort pre-commit hook

Sort import statement in python files

See https://github.com/PyCQA/isort

python_apps/pypo/bin/pyponotify

@@ -17,18 +17,18 @@ Main case:
 
 """
 
-from optparse import OptionParser
-import sys
-import logging.config
 import json
-
-# additional modules (should be checked)
-from configobj import ConfigObj
+import logging.config
+import sys
+from optparse import OptionParser
 
 # custom imports
 # from util import *
 from api_clients import version1 as api_client
 
+# additional modules (should be checked)
+from configobj import ConfigObj
+
 LOG_LEVEL = logging.INFO
 LOG_PATH = "/var/log/airtime/pypo/notify.log"