make aggregate method public.

laravel/database/query.php

@@ -629,7 +629,7 @@ class Query {
 	 * @param  string  $column
 	 * @return mixed
 	 */
-	private function aggregate($aggregator, $column)
+	public function aggregate($aggregator, $column)
 	{
 		$this->aggregate = compact('aggregator', 'column');
 

laravel/database/schema.php

@@ -78,7 +78,7 @@ class Schema {
 		// For some extra syntax sugar, we'll check for any implicit
 		// indexes on the table. The developer may specify the index
 		// type on the fluent column declaration. Here we'll find
-		// any such implicit index and add the actual command.
+		// any implicit indexes and add the commands.
 		foreach ($table->columns as $column)
 		{
 			foreach (array('primary', 'unique', 'fulltext', 'index') as $key)