Remove redundant python imports (#484)

Remove unused imports from all python files that
are not auto generated

bessctl/bessctl

@@ -2,7 +2,6 @@
 import sys
 import os
 import os.path
-import pprint
 import cStringIO
 import tempfile
 import time

bessctl/commands.py

@@ -5,7 +5,6 @@
 import socket
 import fcntl
 import errno
-import glob
 import re
 import subprocess
 import pprint

bessctl/sugar.py

@@ -1,7 +1,6 @@
 import re
 import tokenize
 import parser
-import string
 from StringIO import StringIO
 
 '''

build.py

@@ -3,8 +3,6 @@
 import sys
 import os
 import os.path
-import time
-import urllib
 import subprocess
 import textwrap
 import argparse

container_build.py

@@ -4,7 +4,6 @@
 import subprocess
 import os
 import os.path
-import time
 
 IMAGE = 'nefelinetworks/bess_build:latest' + os.getenv('TAG_SUFFIX', '')
 BESS_DIR_HOST = os.path.dirname(os.path.abspath(__file__))

libbess-python/bess.py

@@ -1,12 +1,7 @@
 import errno
 import grpc
-import inspect
 import os
 import pprint
-import socket
-import struct
-import sys
-import threading
 import time
 
 import service_pb2

libbess-python/bess_test.py

@@ -1,6 +1,5 @@
 import unittest
 import bess_msg_pb2 as bess_msg
-import error_pb2 as error_msg
 import service_pb2
 import grpc
 import bess

libbess-python/protobuf_to_dict_test.py

@@ -1,6 +1,5 @@
 import unittest
 import bess_msg_pb2 as bess_msg
-import error_pb2 as error_msg
 import protobuf_to_dict as pb_conv