Add license info

[chillu]

Otherwise you can't really use this code legally :)

[unclecheese]

Interesting? Do you have an example I can refer to? I had no idea. Do all SS modules need this?

[chillu]

Its just good open source practice (http://opensource.org/). See the LICENSE part of https://github.com/silverstripe/sapphire/blob/3.0/README.md for an example

[drzax]

I second this bug. I'd like to both use this and publish some modifications, but would rather not without some license info.