Add a second binary called ratool for "remote-adapter tool"

[Thib17]

Also a first ratool command: mock-write The remote-adapter tool (ratool) will read an input file in Prometheus exposition text format; translate it in WriteRequest in compressed protobuf format; and send it to the remote-adapter url on its /write endpoint.

[iksaif]

I guess the plan at the end if ratool -> graphite-remote-adapter -> nc ? Would it be possible to simply have file -> graphite-remote-adapter -> file ? The current ratool would still be useful to tests stuff manually, but for unittests it would be easier not to use any network.

[Thib17]

@iksaif I agree. I propose to add both use cases. The mock of a real prometheus write request is usefull while contributing to this project. And The unittest of the config has its own command that don't use any network.

[iksaif]

Add an example of input, output and usage in the README.md

[Thib17]

Done