Add libqt-webkit to jenkins boxes
Add libqt-webkit to jenkins boxes

This adds libqt-webkit package to the jenkins boxes. This will enable
jenkins to run smokey tests with javascript enabled[1].

The same is done is ci-puppet[2]

[1]: https://github.com/alphagov/smokey/pull/221
[2]:
https://github.com/alphagov/ci-puppet/blob/0e51d53779a72df813c63273d0f8e
2bd5b3c858f/modules/ci_environment/manifests/jenkins_job_support.pp#L25

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet