Adds KSLWeatherWidgetToggle

Adds ddm-dropdown as a dependency and creates a new KslWeatherWidgetToggle
tag that use ddm-dropdown to encapsulate the KslWeatherWidget in a
dropdown with a custom toggle that updates based on the selected city
and the weather data ajax updates.
Merge pull request #6 from deseretdigital-ui/dropdownComponent

Adds KSLWeatherWidgetToggle