Change 5.4 specific array syntax into 5.3

This allows to use UrlMap with Builder and Run which supports
5.3 now.

As a side this adds a travis file which tests on 5.3, 5.4, 5,5 and hhvm.

Reasoning for this is we are about to deploy 2 applications that use UrlMap for embedding a Silex application into a Symfony app. Myself i would be glad to just switch to 5.5 and be done with this, but at work it is not my decision sadly.

Is it possible to get a new tagged version aswell if this is merged?