fix FinalDb:dropDb() exclude sqlite_sequence table

Author: yangfuhai

src/net/tsz/afinal/FinalDb.java

@@ -379,7 +379,7 @@ public void dropTable(Class<?> clazz) {
 	 */
 	public void dropDb() {
 		Cursor cursor = db.rawQuery(
-				"SELECT name FROM sqlite_master WHERE type ='table'", null);
+				"SELECT name FROM sqlite_master WHERE type ='table' AND name != 'sqlite_sequence'", null);
 		if (cursor != null) {
 			while (cursor.moveToNext()) {
 				// 添加异常捕获.忽略删除所有表时出现的异常: