No cleanup and more JVM heap space in travis-ci

The workers in Travis-CI have been pdated, now we have more RAM and disk space! Take a look at [that](http://about.travis-ci.org/blog/2013-01-25-the-worker-gets-a-revamp/) :-)

This update is needed so the builds can still pass. Sorry for the mess of commits, but I was trying to figure out what exactly had changed in travis, so I was doing some tests. At the end just two files are changed.

Now we can skip the cleaning up process in travis, so the builds should be faster.