Add LICENSE (copied from upstream)

Original at https://raw.githubusercontent.com/AndreasBriese/bbloom/28f7e881ca57bc00e028f9ede9f0d9104cfeef5e/LICENSE

Fixes #7

LICENSE

+bbloom.go
+
+// The MIT License (MIT)
+// Copyright (c) 2014 Andreas Briese, eduToolbox@Bri-C GmbH, Sarstedt
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy of
+// this software and associated documentation files (the "Software"), to deal in
+// the Software without restriction, including without limitation the rights to
+// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+// the Software, and to permit persons to whom the Software is furnished to do so,
+// subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+siphash.go 
+
+// https://github.com/dchest/siphash
+//
+// Written in 2012 by Dmitry Chestnykh.
+//
+// To the extent possible under law, the author have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+// http://creativecommons.org/publicdomain/zero/1.0/
+//
+// Package siphash implements SipHash-2-4, a fast short-input PRF
+// created by Jean-Philippe Aumasson and Daniel J. Bernstein.