IEP-75 Thin Client MsgPack Serialization for 3.0

[Pavel Tupitsyn]

Igniters,

I have drafted an IEP on thin client serialization format [1],
please review and let me know what you think.

[1]
https://cwiki.apache.org/confluence/display/IGNITE/IEP-75+Thin+Client+Serialization