try to call python3 pip

if there is a pip3 binary call that instead of pip, to better support platforms with bot python 2 and 3

agent.py

 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 from os import environ, chdir
-import platform
 import subprocess
 import sys
+import logging
+from shutil import which
 
 try:  # noqa
     chdir(sys.path[0])  # noqa
-    subprocess.call(('pip', 'install', '-r', 'requirements.txt'))  # noqa
-except Exception:  # noqa
+    pip3_available = which("pip3")
+    if pip3_available is not None:
+        subprocess.call(('pip3', 'install', '-r', 'requirements.txt'))  # noqa
+    else:
+        subprocess.call(('pip', 'install', '-r', 'requirements.txt'))  # noqa
+except Exception as e:  # noqa
     pass  # hope it works  # noqa
 
-
-from twisted.internet import reactor, defer
-from twisted.internet.task import LoopingCall
-
-
-import uptime
-import logging
-from inspect import getfullargspec, isfunction
-
-from agent.SerialLineReceiverBase import SerialLineReceiverBase
 from agent.agent import init_serial, reactor
 # Note: Import everything because later we need to use the BaseContext
 # (relative import error.