Add slam tool to consensus server repo

[cbeck88]

The slam tool is a load testing tool for the consensus servers.
Generally, test code should be versioned with the code under test.

This moves the slam tool to the same repo as the consensus servers,
and will make it easier to run this test in CD and more easily use
it to validate changes to the consensus servers.

[eranrund]

Some documentation things need to be improved but we know the code is doing its job :)

[cbeck88]

@jcape lmk if the updates for HardcodedCredentialsProvider looks right, i mostly copied from mobilecoind

Do you guys think the crate should be mc-slam now?

[jcape]

Do you guys think the crate should be mc-slam now?

Yep (will review inline for the HCP stuff)

[jcape]

LGTM, assuming it runs properly against deployed networks. I'd remove some of the weird stuff from README.md, though, like references to specific networks or repositories that people may not have access to...

[cbeck88]

TODO:

• deploy and run slam as in instructions

in discussion with Sara, we will improve the README at a later date. if we do this we have one less thing to worry about when open sourcing fog repo