We need to allow the snapshot applet to run.

If the Security Kit module is installed we provide the needed policies
for allowing the Snapengage widget in the Content Security Policy
header.

This is fragile since we have no clue whether Snapengage changes the
widget.

See https://www.drupal.org/project/seckit

git authored May 29, 2013 and Arne Jørgensen committed May 29, 2013

Issue #2006222 by moxojo: Added Clarify what the 'advanced code' is and only output the advanced code snippet if the field has been filled out.

Use `git log` if you are curious.

(cherry picked from commit a910a743)

Thanks go to Eugene Ilyin:
http://drupal.org/node/1429208#comment-5561768.

Although not very likely that a user with permissions to set the
widget ID would abuse it for XSS attacks there is really no reason to
not protect it.

Test cases is heavily based on the test cases from Google Analytics
module.

Should have been part of commit
6db43b1e.

Use php_eval() instead if php.module is enabled.