Support for distributed frameworks

[berryjam]

For producing environment,I think that it is necessary of zksync to support for distributed framework.

Considering the following situations:

• Single point problem.(It couldn't service at all when the only one server is down.)
• The main components of zksync communicate with each other by threads' channel.Distributed services will use rpc to interact with others instead.
• Transaction per second of zksync will also be limited by single one framework.(e.g Application like the perpetual contract that will reach more than thousand query per second.)But how to keep the zksync state of all server being consistent is another tricky problem.
• It couldn't service when need publish or restart.(e.g fixing bugs or publishing new features)

May be it is time to develop distributed mode for zksync in sometime with its widely used as a leading open source zk framework.

Thanks.