title: ImportError: cannot import name SignedJwtAssertionCredentials
body: <p>I'm trying to access a google app through the Python Client using this code to gain authorization (private info obviously redacted): </p>
  
  <pre><code>import gflags
  import httplib2
  
  from apiclient.discovery import build
  from oauth2client.file import Storage
  from oauth2client.client import SignedJwtAssertionCredentials
  from oauth2client.tools import run
  
  f = open('privatekey.p12', 'rb')
  key = f.read()
  f.close()
  credentials = SignedJwtAssertionCredentials(
      service_account_name='name@developer.gserviceaccount.com',
      private_key=key,
      scope = 'https://www.googleapis.com/auth/calendar')
  http = httplib2.Http()
  http = credentials.authorize(http)
  service = build(serviceName='calendar', version='v3', http=http)
  </code></pre>
  
  <p>Yet I receive this error: </p>
  
  <pre><code>ImportError: cannot import name SignedJwtAssertionCredentials
  </code></pre>
  
  <p>I have installed the Google v3 API Python Client as well as OAuth2; I don't seem to be having any other problems with those modules, though I haven't used them much. Anyone know what's going on? </p>