Write function for background theme change

[crowandrew]

As a User
I want to see the app theme match the weather
So that I feel the site to be more reactive an engaging

switch statement to apply backrground/theme change
switch(expression) {
case sunny:
(content)=sunnyWeatherTheme
break;
case cloudy:
(content)=cloudyWeatherTheme
break;
default:
(content)=defaultAppTheme
}

Acceptance Criteria

• Function should be named themeChange
• Requests the short forecast from the localWeather function
• Matches short forecast
• Uses a switch statement as outlined above
• Set default if nothing matches short forecast
• Change classes on set elements when short forecast matches a theme