Add wanderBehavior and chaseBehavior spec
add astar function
connect wander behavior with player
update wander mode to respect  player's width & height size;
update player direction in wander mode
use web worker for A* if possible
update chase behavior
update GuardianBehavior to be able to manage state transition between wander and chase
update .gitignore to ignore minified files
Merge branch 'ai_system'
remove hammer.js reference
change A* goal state checking to use intersection check
Merge branch 'ai_system'