Added reachability (check wifi vs 3g)

reachability.py

@@ -0,0 +1,20 @@
+# coding: utf-8
+from objc_util import *
+
+NSBundle.bundleWithPath_('/System/Library/PrivateFrameworks/SoftwareUpdateServices.framework').load()
+
+def currentNetworkType():
+	''' 0: none
+	1: wifi
+	2+: cellular'''
+	netMon=ObjCClass('SUNetworkMonitor').sharedInstance()
+	return netMon.currentNetworkType()
+def main():
+	networkType=currentNetworkType()
+	assert networkType>0, 'Network Not Connected'
+	if networkType>1:
+		ok_to_continue=raw_input('Using cellular data. Continue downloading? [y/n]')
+		assert ok_to_continue.lower()=='y', 'User Cancelled'
+
+if __name__=='__main__':
+	main()