我觉得PROGRESS_SIZE 为default还是有点大，希望能增加个值small

[Aarthas]

我觉得PROGRESS_SIZE 为default还是有点大，希望能增加个值small

1. progress_size_type 加个small，
2. private final static int DEFAULT_PROGRESS_SIZE = 50;
   private final static int BIG_PROGRESS_SIZE = 60;
   加个private final static int SMALL_PROGRESS_SIZE = 40;