Validates a given configuration.

@param {Object} config - A configuration.
@return {Promise} A promise that returns the given configuration.
function validateConfig(config) {

	return new Promise((resolve, reject) => {

		if(config.src !== undefined) {

			if(!Array.isArray(config.src)) {

				config.src = [config.src];

			}

			resolve(config);

		} else {

			reject("No source path specified");

		}

	});

}