add support for optional callback

closes sindresorhus#60

index.js

@@ -13,7 +13,7 @@ function log(str) {
 	write(str + '\n', 'utf8');
 }
 
-module.exports = function (grunt) {
+module.exports = function (grunt, callback) {
 	var now = new Date();
 	var startTimePretty = dateTime();
 	var startTime = now.getTime();
@@ -146,6 +146,13 @@ module.exports = function (grunt) {
 		// `grunt.log.header` should be unhooked above, but in some cases it's not
 		log('\n\n' + chalk.underline('Execution Time') + chalk.gray(' (' + startTimePretty + ')'));
 		log(formatTable(tableData) + '\n');
+
+		if (callback) {
+			callback(tableData, function() {
+				process.exit(exitCode);
+			});
+			return;
+		}
 		process.exit(exitCode);
 	});
 };

readme.md

@@ -21,6 +21,19 @@ module.exports = function (grunt) {
 }
 ```
 
+## Optional Callback
+
+If you want to collect the timing stats for your own use, pass a callback to time-grunt:
+
+```js
+require('time-grunt')(grunt, function(stats, done) {
+	// do whatever you want with the stats
+	uploadReport(stats);
+
+	// be sure to let grunt know when to exit
+	done();
+});
+```
 
 ## Clean layout