Don't make request on user login if API credentials are not set

[Nikschavan]

In most of the places, the plugin checks if the API credentials are set or not and then makes requests to sailthru, for example -

sailthru-wordpress-plugin/classes/class-sailthru-content.php

Lines 595 to 606 in eb21493

	// Get the content options to see if we want to fire the API.
	$options = get_option( 'sailthru_content_settings' );
	// Check to see if Content API is disabled in the UI
	if( !isset ($options['sailthru_content_api_status'] ) || "false" === $options['sailthru_content_api_status'] ) {
	return;
	}
	// See if a filter has disabled the content API, this may be done to override a specific use case.
	if ( false === apply_filters( 'sailthru_content_api_enable', true ) ) {
	return;
	}

However, in the user login flow, the API credentials are not checked, and thus, the requests fail, and the error objects are logged to the error logs.

In non-production and local environments where these API credentials are not set, this keeps adding logs and making it difficult to debug actual errors.

sailthru-wordpress-plugin/plugin.php

Lines 281 to 286 in eb21493

	if ( get_option( 'sailthru_setup_complete' ) ) {
	$sailthru = get_option( 'sailthru_setup_options' );
	$api_key = $sailthru['sailthru_api_key'];
	$api_secret = $sailthru['sailthru_api_secret'];
	$client = new WP_Sailthru_Client( $api_key, $api_secret );