Edit make time slots task so that it can check if it is the first day of the current month.

I did this so that the task can be called by heroku scheduler daily, but then only run once each month.

I'm not sure why files from my previous emails branch are included in this PR.  Please focus on model CreateTimeSlots and make_time_slots.rake
If there are any css classes you think you may never use, it may be worth removing them, just to reduce the size of the email, but not a biggie.