Updated weather.js

Updated the weather.js to use a dictionary of the possible weather
variables rather than a big chain of if/else statements. Performs
quicker and looks cleaner.
Added extra weather descriptions. Should cover everything for now.
check to see whether the json.StandardObservation.text pulled out a
match from the dictionary failed regardless. Updated to check whether
it failed or not and display *something*.
This is why I shouldn’t code at 1am. Left in test case rather than the
live json result. D’oh.
Merge pull request #1 from lukewhitt/master

Updated weather.js (thanks Lukewhitt!)