use tap to run tests so we get a real exit code
fix test errors (only on travis)

possibly due to monkey-patching of npmlog, tests relying
on the log buffer fail because values have an extra leading
space. all tests pass locally and on SD... :/
restore log after rebase fun
mock a functional run() for `gv`
modify built-ins to use cb(), do not test log.record
do not use log.buffer for tests
remove redundant tests, test --libmojito
test variation, env.mojito false.
re-work help also; use cb() not log.record