Implement in erlang Elixir's task

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Check:

• http://elixir-lang.org/docs/stable/elixir/Task.html
• https://github.com/josevalim/xgen/tree/master/lib/task

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We can implement it with with async_call(Node, Module, Function, Args) -> Key
http://erlang.org/doc/man/rpc.html#async_call-4

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A module that evaluates a fun is needed

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Check concurrency control fom https://github.com/duomark/epocxy