[rabit harden] Enable all tests (#90)

* include osx in tests
* address `time_wait` on port assignment
* increase submit attempts.
* cleanup tests

python/rabit.py

@@ -4,7 +4,7 @@ Reliable Allreduce and Broadcast Library.
 Author: Tianqi Chen
 """
 # pylint: disable=unused-argument,invalid-name,global-statement,dangerous-default-value,
-import cPickle as pickle
+import pickle
 import ctypes
 import os
 import sys
@@ -99,9 +99,10 @@ def init(args=None, lib='standard', lib_dll=None):
         When this is presented argument lib will be ignored.
     """
     if args is None:
-        args = sys.argv
+        args = []
     _loadlib(lib, lib_dll)
     arr = (ctypes.c_char_p * len(args))()
+
     arr[:] = args
     _LIB.RabitInit(len(args), arr)