Updating Thucydides plugin to work with Content Security Policy changes

[Harry King]

Hi,

Been using Jenkins for 2+ years, and the Thucydides Test Report plugin I've been relying on is no longer compatible with the latest releases of Jenkins.  So I dug in and made some changes locally, and I've got a local copy of the plugin working nicely.  I've pushed my changes up and raised a pull request, However, findbugs is complaining about two issues unrelated to my change (I suspect the last commit to this plugin was before findbugs was introduced), and I've had no other input on the PR.  Would someone mind taking a look?