[Optional]support cron task

[halfcrazy]

Syntax may looks like this:

@cron((Seconds,Minutes,Hours,DayofMonth,Month,DayofWeek))
def fn():
    pass

or unix like syntax like this:

@cron('* * * * *')
def fn():
    pass

In the cron decorated function, use slacker to send messages.
So, the bot can send daily reports.

[halfcrazy]

http://stackoverflow.com/questions/25639221/how-to-run-recurring-task-in-the-python-flask-framework