added lang::has method.

laravel/lang.php

@@ -73,6 +73,18 @@ class Lang {
 		return new static($key, $replacements, $language);
 	}
 
+	/**
+	 * Determine if a language line exists.
+	 *
+	 * @param  string  $key
+	 * @param  string  $language
+	 * @return bool
+	 */
+	public static function has($key, $language = null)
+	{
+		return ! is_null(static::line($key, array(), $language)->get());
+	}
+
 	/**
 	 * Get the language line as a string.
 	 *