Fixed a bug that crashed program when TDA didn't have enough data on the symbol
* The calculation of average true range threw an error for certain symbols like FRSH because
  the TDA API was returning only a handful of candles with '0' for all the values. I inserted some
  code that screens out these circumstances by throwing out symbols with less than 61 candles returned
  over a 2-day period. I think the handling of the watchlist is a little sloppy and could
  probably use some refactoring later.
* Also added sleep function to the scheduler in run_alerts.rb. Found out that an infinite loop
  could eat up system resources.
Enhanced the way it processes after hours so it doesn't give too many alerts. Now looks for percent change over ATR.