Basic CSRF protection

It's by no mean a bullet proof protection against CSRF but it
provides a first protection.
Waiting for a better alternative, it's better than stay naked

Change-Id: Ibf666557659295d427ffb43657d3e61b88b5fb41
Merge commit 'refs/changes/36/1636/1' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  Basic CSRF protection

Change-Id: If91eeab92f9c8703aeaec49dbce2e104069bdafb
This is Tuleap 6.8.99.30

Change-Id: I0b856e81f6d3141da0fb1eaee896da2b9254f6f2