Time Zone support

[gainskills]

Hi there,

Thanks for your effort on this awesome plugin.

I'm a fresher to Ruby and struggled on this plugin's timezone setting, related issues:

• Using timezones other than UTC #25
• Next run date constantly increasing. #79

What I proposed are:

1. Refer to @alexander-sessa 's suggestion, made the next run time in the new periodic task is possible
2. Fix the time of 'next run time' is fixed '09:00:00; when the 'business day' option is enabled.

I would say what I changed is not the best solution, reason: For -2, the time is changing because of time.now changes while crontab won't run the task right after the scheduled time. All I want to do is sharing what I did and hope it could be a hint for the final solution.

Thanks,

[dobriand]

I have the same problem, the time of 'next run time' is fixed '09:00:00; when the 'business day' option is enabled.