Add alwaysAllowAccess flag to traffic controller

  + This flag allows access to logs for any app with any credentials,
    thus the traffic controller does not have to talk to cloud controller.
    This is to support deploying loggregator outside of CloudFoundry.

  + Also converts the log_access_authorizer_test to Ginkgo.

Signed-off-by: Matthew McNew <mmcnew@pivotal.io>
Logs are accessible without auth headers with alwaysAllowAccess flag

  + Pulls empty auth header check into authorizers
  + Also makes alwaysAllowAccess flag apply to Admin Firehose access.

Signed-off-by: David Julia <djulia@pivotal.io>
Rename alwaysAllowAccess flag to disableAccessControl.

Signed-off-by: Matthew McNew <mmcnew@pivotal.io>
Merge pull request #31 from dajulia3/master

Add disableAccessControl flag to traffic controller