Tweaked player ship movement and began adding player lives hud

Changes Made:
player.js :
- fixed jerky ship motion along border (move border collision check
after the ship movement update)
- added a new variable called playerLives to tell the hud how many
player lives to initially show. will update this later

hud.js - starting implementing the player lives count in hud. will
update later

events.js - noticed there was no key-up check for escape key. Added
that.

startState.js - removed the escape key check on start screen. Didn't
need it.