added the extend option to the forecast.io query, ref. "22 May 2013: Added the extend option."
Merge pull request #6 from rhfung/master

added the extend option, ref. "22 May 2013" changes to Forecast.io
Updated to match Forecast.io API: Added extend hourly option, CA & Auto units, Dew Point, Ozone, PrecipIntensityMax, PrecipIntensityMaxTime, updated examples and README.  Updated podspec
Merge branch 'pr/6'
Added "Thank You" section to readme for contributors :)