Added LICENSE file

[warmans]

My company is strict about licencing (even for dev deps) and require an explicit licence file for vendored projects rather than simply naming the licence. I believe this is due to the possibility that the licence will change over time and without the file it's not clear what terms were agreed to. Anyway it would be much appreciated if you added the LSC licence file.

Thanks.

[patricksmms]

@geelen, @sokra, @timdorr, @TrySound, @sullenor, @douglasduteil, any chance of getting this merged to master and the npm package published?

[sullenor]

I published version 1.2.1, but it is still under the next tag and I don't remember why :)
If you need to update the latest version — tell me.

[patricksmms]

@sullenor, thanks a lot!