Update Cron.cs - MinuteInterval & HourInterval

[staviloglu]

Updated MinuteInterval & HourInterval methods to make them available (not obselete) again.

Added defensive code against interval value to get rid of the problem described in #1041

@odinserj

Also related:
#1054
#1779

[odinserj]

Thanks @staviloglu, this is an interesting way of providing the feature while trying to avoid its potential problems. However I still believe that one day there's much better implementation of this with proper intervals based on duration and not on the Cron format, and I believe sometimes it's much better to leave pain points to have more motivation of fixing them in full.

[staviloglu]

@odinserj I totally understand you but also know that many people still use these methods even if they are obselete and they may or may not be informed about the issue #1041.

This PR, if they check change-logs or update their version of Hangfire, would inform anyone who uses these methods.

I need to confess that I still want to use those methods with the proper values 😄

Anyway, thanks for your time and this awesome library, keep up the good work.