minor bug fix
Merge pull request #97 from jackykschou/JackySprint10

Jacky sprint10
Merge pull request #98 from jackykschou/JackySprint10

updated logics of difficulty curving
Merge branch 'develop' into BrandonSprint10

Conflicts:
	UnityProject/Assets/Scenes/GameStart.unity
	UnityProject/Assets/Scripts/GameScripts/GameLogic/GUI/ButtonController.cs
Updated Layouts of Survival Level with new difficulty enemies
Merge pull request #99 from jackykschou/BrandonSprint10

Brandon sprint10
Merge branch 'develop' into JackySprint10