Command Line Tool

[Hoverbear]

This extends #16 in many ways.

This issue proposes we add a feature command-line which enables a binary (src/bin/client.rs) via the required-features field of [bin].

This binary would allow users to call, for example:

$ tikv-client --pd ${PD} raw set key value
$ tikv-client --pd ${PD} raw get key
value

Closing this issue starts by opening an RFC to define the calling conventions. Due to the size of the issue it's advisable to start with raw first, then add transactional later.

[nrc]

This is RFC 21: https://github.com/tikv/rfcs/pull/21

[Hoverbear]

@sciamp-dev is working on this! Yay :)