refactor(Controls): reduce size of button methods
refactor(Controls): reduce size of button methods

The Button script methods have been reduced in size by
breaking large methods up into smaller methods to make the
code easier to read.

TMaloteaux/SteamVR_Unity_Toolkit,mattboy64/SteamVR_Unity_Toolkit,thestonefox/SteamVR_Unity_Toolkit,virror/VRTK,Fulby/VRTK,gpvigano/SteamVR_Unity_Toolkit,red-horizon/VRTK,adamjweaver/VRTK,thestonefox/VRTK,gomez-addams/SteamVR_Unity_Toolkit,gpvigano/VRTK,Innoactive/IA-unity-VR-toolkit-VRTK