Add a Staple SceneElement in SurgSim::Blocks and update CMakeList.txt.
Add feature to create staple on button push.

- Create AddStapleBehavior to automatically add staple when a button is pushed.
- Create a SceneElement that connected the AddStapleBehavior and the Stapler.
- Update CMakeLists.txt
Merge remote-tracking branch 'origin/wip/stapler-Demo' into wip/stapler-Demo-inputVTC

Conflicts:
	Examples/StaplingDemo/main.cpp
Style revision of StapleElement class
Put class AddStapleBehavior into namespace SurgSim::Blocks.

1. Add documentations.

2. Use forward declaration.

3. Coding style revision.
Put class StapleElement into namespace SurgSim::Blocks

Add documentations.
Re-enable adding staple from input (mistakenly removed by last merge)
Keep AddStapleFromInputBehavior under SurgSim namespace for now.
Add empty namespace for AddStapleBehavior.
Update scope of addStapleBehavior in main.cpp and InputComponent's
forward declaration.
Fix typo and SURGSIM::ASSERT() output format in main.cpp
Merge remote-tracking branch 'origin/wip/stapler-Demo-inputVTC' into feature/staplingDemo
Fix path to load staple in StapleElement, add reference for staple size
Use actual .obj files instead of collision obj files
Drop "collision" in file names in main.cpp and StapleElement.cpp
Move StapleElement out of namespace SurgSim::Blocks

Also, move source cod files of StapleElement in Example folder.
CppLint warning fix