Update Trac security warnings

[nacin]

When you try to submit a ticket in the Security component, Core Trac will display a notice. This has probably helped some, but we still get (often bogus) security reports created sometimes.

We should instead detect words referring to a security issue, then display a checkbox and force them to click it before they can submit the ticket.

[nacin]

In 218:

Trac: Add JavaScript to detect words probably referring to a security report. props jorbin. see #265.

[nacin]

In 219:

Trac: Add trac-security.js to /newticket views. fixes #265.

[jorbin]

Patch attached is a version that contains passing unit tests ​https://github.com/aaronjorbin/trac_security

[nacin]

In 1058:

Update Trac security script. props jorbin, fixes #265.