Add weather command

Uses UTF8 characters and assumes fixed-width font. It might look rather
atrocious otherwise. Should cache weather feed to prevent spamming the
service.
Cleanup weather.pm
Merge branch 'feature/weather' of https://github.com/tlcine/odchbot into tlcine-feature/weather
Added in caching for weather by default it's one hour
Although the degrees symbol is showing up wonky in my client I've
altered a couple of things for readability and am happy to commit the
lion share of this. This will be a TODO for the future.