SLING-2954 - Event ITs spuriosly fail on Jenkins

Update pax-exam version and pax-url versions to be similar to the
healthcheck and installer ITs. Not sure if it will do good, but it
definitely won't hurt.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1501393 13f79535-47bb-0310-9956-ffa450edef68
SLING-2958 - Spurios test failures in GeneratedNodeNameTest 

Cleanup generated content between test method invocations, to ensure
that there are no conflicts due to method execution order.

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1501532 13f79535-47bb-0310-9956-ffa450edef68
Set up experimental travis build
travis: use mvn -q to try and complete the build on Travis