Dijkstra and enemies

Basic enemy skeleton, implemented Dijkstra’s algorithm in Grid
Merge branch 'dev' into #70-Enemies
Door to be visible
Concurrency fix in BombScheduler
Resolve SimulationTimer deadlock scenario
Fix Grid test
Add test to ensure door can be covered
Make Doors indestructible
ServerTest to use proper testGrid
Cover grid1.json door with wall
Do nothing if player move command received after its death
Random Monster

Monster moves randomly…stalls once in a while (probably an error with
calculating possible moves)
Line and PathFinding enemies now functional
Refactoring
Merge pull request #95 from oharaandrew314/#73-visible-doors

#73 visible doors
Merge remote-tracking branch 'origin/dev' into #44_player_collision_fix
Merge pull request #99 from oharaandrew314/#70-Enemies

#70 enemies
Merge remote-tracking branch 'origin/dev' into #44_player_collision_fix

Conflicts:
	src/server/controllers/Server.java
Merge pull request #104 from oharaandrew314/#44_player_collision_fix

Do nothing if player move command received after its death
Merge branch 'dev' into #87-powerups

Conflicts:
	src/common/models/Player.java