* Problem: acceptance-test suite is not documented
Solution: add README.md in the root of the acceptance tests, unify
`Makefile` and commands, remove more cached files when `make clean` is
ran.
* Problem: documentation does not mention Makefile
Solution: update docs with our new and shiny commands
* Problem: Some docs still say to run MongoDB w/ replica set
Solution: Update the relevant docs
* Problem: A docs mention of upsert-validator wasn't linked to BEP-3.
Solution: Link that docs mention to BEP-3 on GitHub.
