Simplify HTTPBasicAuth arguments.

This makes sf2github compatible with older python-requests
versions, such as 0.8.2 (shipped e.g. with Ubuntu 12.04).

issues.py

@@ -34,17 +34,16 @@
 from time import sleep
 from getpass import getpass
 import requests
-from requests.auth import HTTPBasicAuth
 import json
 import re
 
 def __rest_call_unchecked(method, request, data=None):
     global github_repo, github_user, github_password
     url = 'https://api.github.com/repos/%s/%s' % (github_repo, request)
     if method == 'PATCH':
-        response = requests.patch(url, data=json.dumps(data), auth=HTTPBasicAuth(github_user, github_password))
+        response = requests.patch(url, data=json.dumps(data), auth=(github_user, github_password))
     else:
-        response = requests.post(url, data=json.dumps(data), auth=HTTPBasicAuth(github_user, github_password))
+        response = requests.post(url, data=json.dumps(data), auth=(github_user, github_password))
     # GitHub limits API calls to 60 per minute
     sleep(1)
     return response