Merge branch 'dnoble/Reject-invalid-credentials-on-setup' of https://github.com/splunk/splunk-app-twitter into dnoble/Reject-invalid-credentials-on-setup

Signed-off-by: David Noble <dnoble@splunk.com>
Merge branch 'dnoble/Reject-invalid-credentials-on-setup' of https://github.com/splunk/splunk-app-twitter into dnoble/Reject-invalid-credentials-on-setup