Removed responsibility to load Player data from AppDelegate.
    Home View Controller, the main View Controller, now does this.
Created PlayerController to handle Player data.
    Implemented level up, gain experience, reduce / gain energy.
    Implemented Alert that appears when energy is zero and Battle is attempted.
        Will restore energy if you "pay".
Added "key" property to Enemy to be able to access them from the Enemy Store.
    Updated JSON Controller accordingly.
Added notifications for Battle Start Attempt, Battle Start, Battle End.
Added notifications to handle the changing of player stats: Level, Experience, Energy, Name.
Implemented Player energy reduction on Battle Start
    Changed implementation of Battle Start to make an Attempt first
        If Player has enough energy, deduct energy cost then proceed
Added Player stat labels to Home Header View. They update when the relevant notifications are posted.
Fixed issue with Player Store that caused infinite setter calls.