Fix dependency installation for Travis
Fix dependency installation for Travis

Build was failing with
$ apt-get install libxml2-utils
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?

APT dependencies must be installed as sudoer.

mr-c/Galaxy-XSD,JeanFred/Galaxy-XSD