Signed requests can now be generated and transmitted by the client.

Signed requests can now be generated and transmitted by the client.

Example code:
    require 'google/api_client'
    client = Google::APIClient.new(:service => 'buzz')
    client.authorization.fetch_temporary_credential!(
      :additional_parameters => {
        'scope' => 'https://www.googleapis.com/auth/buzz'
      }
    )
    client.authorization.authorization_uri
    # Redirect user here
    client.authorization.fetch_token_credential!(:verifier => '12345')
    response = client.execute(
      'buzz.activities.list',
      'scope' => '@self', 'userId' => '@me', 'alt' => 'json'
    )
    status, headers, body = response

git-svn-id: https://google-api-ruby-client.googlecode.com/svn/trunk@34 c1d61fac-ed7f-fcc1-18f7-ff78120a04ef