Timer module. WPA Handshake attack is prettier.

1. Timer module for timing things. Should've done this a while ago.
2. WPA handshake attack outputs # of clients, lists all clients, has countdown
3. WPA Handshake Attack deauths all clients at the same time.
4. Fixed bug where WPA handshake attack never timed out. Fixes #23
5. WPA Cracking via aircrack-ng shows percentage & ETA.
6. Mild refactoring / cleanup of AttackWPA module.

py/Timer.py

@@ -0,0 +1,36 @@
+#!/usr/bin/python2.7
+# -*- coding: utf-8 -*-
+
+import time
+
+class Timer(object):
+    def __init__(self, seconds):
+        self.start_time = time.time()
+        self.end_time = self.start_time + seconds
+
+    def remaining(self):
+        return max(0, self.end_time - time.time())
+
+    def ended(self):
+        return self.remaining() == 0
+
+    def running_time(self):
+        return time.time() - self.start_time
+
+    def __str__(self):
+        ''' Time remaining in minutes (if > 1) and seconds, e.g. 5m23s'''
+        return Timer.secs_to_str(self.remaining())
+
+    @staticmethod
+    def secs_to_str(seconds):
+        '''Human-readable seconds. 193 -> 3m13s'''
+        rem = int(seconds)
+        hours = rem / 3600
+        mins = (rem % 3600) / 60
+        secs = rem % 60
+        if hours > 0:
+            return "%dh%dm%ds" % (hours, mins, secs)
+        elif mins > 0:
+            return "%dm%ds" % (mins, secs)
+        else:
+            return "%ds" % secs