Documentation Update

Documentation for final weeks
PushSharp Learning

Sample code for PushSharp. Works to send a notification to the emulator
if you don't reset the app, otherwise you need to change the
registration ID manually.
Push notifications working!

Though still very basic, you can now send push notifications to Zadify,
not just the demo app.
This commit may contain some things that belong in the next commit.
Things are somewhat mixed together.
Work on rewards, GCD IDs

Some work on custom rewards. Once I fixed being able to add custom
rewards, I somehow broke displaying them, so this is still part of a
work in progress.
Also, some documention on GCD IDs I've used. A good deal is useless
except on my computer.