Improve MIGRATION.md, add licensing, start changing README.md

Author: milindl

LICENCE.node-rdkafka-txt

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+The promisified API (lib/kafkajs) is inspired by kafkajs (github.com/tulios/kafkajs).
+The promisified tests (test/promisified) are also adapted from there.
+The license notice is reproduced below.
+
+----
+
+The MIT License
+
+Copyright (c) 2018 Túlio Ornelas ([email protected])
+
+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.

LICENSE.kafkajs

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+This project is based on node-rdkafka (github.com/Blizzard/node-rdkafka).
+The license notice is reproduced below.
+
+--------
+
+The MIT License (MIT)
+Copyright (c) 2016 Blizzard Entertainment
+
+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.