Adds support for cron syntax

[JeffLuckett]

Uses Fugit gem to provide support for cron syntax for scheduling.

Also fixes your Travis build for older rubies.

[afn]

This is a cool feature, but I'd like to avoid adding a dependency unnecessarily. Can you modify this to
just require fugit on demand if the cron option is used, and fail with an appropriate error message if the user doesn't have the gem installed?

We should also have test coverage (it's fine to include fugit as a development dependency).

Finally, since the cron setting overrides causes run_at, run_interval, and tz to be ignored, we should make these mutually exclusive by raising an error if both cron and one of the other settings is set.

[JeffLuckett]

Ok. Wasn't sure if you'd be interested so didn't go too far with it. I'll try to carve up some time to button it up.

…

On Mon, Jun 3, 2019, 3:02 PM Tony Novak ***@***.***> wrote: This is a cool feature, but I'd like to avoid adding a dependency unnecessarily. Can you modify this to just require fugit on demand if the cron option is used, and fail with an appropriate error message if the user doesn't have the gem installed? We should also have test coverage (it's fine to include fugit as a development dependency). Finally, since the cron setting overrides causes run_at, run_interval, and tz to be ignored, we should make these mutually exclusive by raising an error if both cron and one of the other settings is set. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#30?email_source=notifications&email_token=AADSVRD3IV43Y5VT56KVIJ3PYVTFNA5CNFSM4HOW2RGKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGODW2L5AA#issuecomment-498384512>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AADSVRD7LXRXGNSPIA5KEWLPYVTFNANCNFSM4HOW2RGA> .