weather.py, new usage of dice.py, refactoring

WHAT I'VE DONE:
* Added weather.py. The user can now type `hey fetch the weather for the area code [7 digit area code] for me` and the current conditions and forecast for the next week will be outputted. weather.py makes use of Yahoo!'s weather API to do this.
* Added new functionality to dice.py. The new functionality is very basic -- you can now specify the number of sides on the dice which will be rolled. E.g., `hey roll a 23 sided dice for me` or `hey roll a dice that has 64 sides`.
* General refactoring. :)

Cheers! :beers: