Update LICENSE and NOTICE files

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Consolidate some third-party license entries, update readme in binary distribution

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Add Netty to License files

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[FLINK-1024] Enable automated snapshot deployment through Apache's Maven infrastructure
Add ASM to LICENSE file

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Add ScalaTest to LICENSE file

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Add notice to ClosureCleaner

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[Documentation] Move "How to contrib"; "coding guidelines" out of the code repo (part of FLINK-1012)
Improve build instructions with respect to Hadoop 1 and Hadoop 2 dependencies.
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