Updated Travis build image to use master branch.

Author: Bilge

README.md

@@ -17,7 +17,7 @@ Requirements
   [Releases]: https://github.com/ScriptFUSION/Porter/releases
   [Version image]: https://poser.pugx.org/scriptfusion/porter/v/stable "Latest version"
   [Build]: http://travis-ci.org/ScriptFUSION/Porter
-  [Build image]: https://travis-ci.org/ScriptFUSION/Porter.svg "Build status"
+  [Build image]: https://travis-ci.org/ScriptFUSION/Porter.svg?branch=master "Build status"
   [Coverage]: https://coveralls.io/github/ScriptFUSION/Porter
   [Coverage image]: https://coveralls.io/repos/ScriptFUSION/Porter/badge.svg "Test coverage"
   [Style]: https://styleci.io/repos/49824895