Address Security recommendations provided by Mozilla Observatory

[michaelhidalgo]

The new Mozilla service, namely Observatory, provides a scan for some security misconfigurations.
Unfortunately it gave a "F"

Here is the scan link https://observatory.mozilla.org/analyze.html?host=www.teammentor.net

[romichg]

This looks like their main issue is CSP. I remember we worked a bit on adding CSP support. I think it is part of client customization but didn't make it into the main branch.

HSTS should be easy enough to add.