JENKINS-18894: Do not include coverage column in new Dashboards by default

Change default to not include the coverage column by default in new Dashboards, existing Dashboards should not be affected. 
Also update some of the .jelly files to apply XSS prevention and add more description.
Finally version 1.95 of maven-hpi-plugin is now required in order to use hpi:run for testing the plugin during development because of an incompatibility in 1.94.