Cleaning up foreign key support. Added drop_foreign command.

Signed-off-by: Taylor Otwell <taylorotwell@gmail.com>

laravel/database/schema/table.php

@@ -207,6 +207,17 @@ class Table {
 		return $this->drop_key(__FUNCTION__, $name);
 	}
 
+	/**
+	 * Drop a foreign key constraint from the table.
+	 *
+	 * @param  string  $name
+	 * @return void
+	 */
+	public function drop_foreign($name)
+	{
+		return $this->drop_key(__FUNCTION__, $name);
+	}
+
 	/**
 	 * Create a command to drop any type of index.
 	 *
@@ -216,7 +227,7 @@ class Table {
 	 */
 	protected function drop_key($type, $name)
 	{
-		return $this->command($type, array('name' => $name));
+		return $this->command($type, compact('name'));
 	}
 
 	/**