Resolves #46 #49 #51 #52 #53

[cobbdb]

Resolves #46 #49 #51 #52 #53

From changelog:

• Expose slot.gpt to decouple GPT slot from Harmony slot.
• Slot option interstitial changed to outofpage.
• Slots are no longer defined in GPT until they are displayed. This is an effort to fix how Harmony behaves under Single Request Mode.
• Removed hide.slot() and hide.group() actions.
• Slot display styles are no longer altered by Harmony.
• Added support for ActiveView's impressionViewable event.
• Removed harmony.hasSlot().
• Merged harmony.show and harmony.refresh into only harmony.show.
• Break up harmony.load into load.targeting, load.slots, and load.breakpoints.