Feature/capture parallel set exceptions

[drichert]

If I ran into a timeout or other exception when running commands via Rye::Set in parallel, it would prevent me from getting results for the rest of the boxes in the set.

This change saves any exceptions in a Rye::Rap and appends it to the results.

Wasn't clear on how your test suite works. I'll gladly add tests if you could provide some guidance.

[delano]

Looks great. I'll pull this in now.

The tests are in try/ and tested with Tryouts. The test description and result are in comments which is unconventional but I prefer it b/c the tests double as example code.

https://github.com/delano/tryouts

[ruebot]

drichert++