weekday => 'all' fails on solaris

[purplexa]

Solaris fails with weekday => 'all' because 7 is not a valid weekday number per the POSIX definition of the crontab format (Vixie cron supports 0 or 7 to refer to Sunday, but the POSIX formats only describes 0, and Solaris tends to be stricter about these things).

Either weekday => 'all' should mean range(0,6) or, more simply, just set the value to '*' or 'absent', either of which will accomplish the same thing.

[gordonmessmer]

Does PR #29 fix this for you?