add a header to ensure chrome44+ will display all fillbar correctly

[RoCat]

chrome44+ and latest chromium builds add a security check to inline scripting that prevent in that project to display all fillbars with a warning in the console when using the route "/coverage".

I add a header Content-Security-Policy to allow unsafe-inline, seems to solve that problem and all fillbars are now correctly displayed.

the bug seems not to appear on downloaded html report, only online reports (localhost:XXX/coverage"