Small Additions

Turned Ammo prefab into EnemyAmmo and PlayerAmmo.  NPC1 will deactivate
if health falls to zero in space maze. Experimented with camera. There
is a WoW style camera you can try in Space Maze, but it does weird
things. I scaled down models in Space Maze so that they are around the
same size as in Grassy Field.  I still have not added NPC1Health, etc.
to Grassy Field.  There are no WordGems there yet either.
Small Fixes

Added some scripts and functionality to Grassy Field so that now NPC can
lose life and heal itself with word gems. If NPC health is below 4, it
will seek out a gem to heal itself.

Bug Fixed - Word Gem was giving NPC two hit points instead of one. It
was a collider issue. Two colliders on NPC causing OnCollisionEnter
function to be called twice.

Also organized some scripts into folders.
Merge pull request #12 from galaxode/master

Small Additions