add travis to readme [ci skip]

README.md

@@ -1,4 +1,4 @@
-Multi Theft Auto: San Andreas
+Multi Theft Auto: San Andreas [![Build Status](https://travis-ci.org/multitheftauto/mtasa-blue.svg?branch=master)](https://travis-ci.org/multitheftauto/mtasa-blue)
 -----------------------------
 
 [Multi Theft Auto](https://www.multitheftauto.com/) (MTA) is a software project that adds network play functionality to Rockstar North's Grand Theft Auto game series, in which this functionality is not originally found. It is a unique modification that incorporates an extendable network play element into a proprietary commercial single-player PC game.