Q4 2017 Refactor

• Polymer 1.x/2.x hybrid support
• range property no longer exists - use fromMoment and toMoment as the source of truth - fixes problem of flickering / multiple event calls when any of the three were updated in the past
• Panel can have an empty state
• Updated min and max to minDate and maxDate to align with field
• Added fromMoment and toMoment arguments to validate function call
• Updated tests