put datetime dependency only in libwifi

This closes #20

krackattack/krack-test-client.py

@@ -11,7 +11,6 @@ logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
 from scapy.all import *
 from libwifi import *
 import sys, socket, struct, time, subprocess, atexit, select, os.path
-from datetime import datetime
 from wpaspy import Ctrl
 
 # FIXME:

krackattack/libwifi.py

@@ -4,6 +4,7 @@
 # See README for more details.
 from scapy.all import *
 from Cryptodome.Cipher import AES
+from datetime import datetime
 
 #### Basic output and logging functionality ####