As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
This is more of a meta thing, since it's not seeing active development,
but is just a way for me to build some Serenity parts and include them
in other projects. Move it out of the root to keep things tidy.
