Check behaviour of Everytime/Anytime scripts, and one-time scripts, wrt and hashing

Ref https://github.com/chucknorris/roundhouse/issues/424

* What does grate do if an Anytime/Everytime script is changed, and re-run?
* What does grate do if we change a one-time script, and we run with `--warnononetimescriptchanges`
* On the _next_ run, make sure we use the _latest_ run of the script to compare the hash, not a random one.