Add LeapMotion SDK support

- Add the leapmotion folder in interface/external
- Add the "FindLeapMotion.cmake" file in cmake
- Add the first iteration of the class LeapMotionManager.h and .cpp in
the interface/devices folder
- Tested only on windows  7 so far
Delete LeapMotionManager.h
Delete LeapMotionManager.cpp
Revert "Add LeapMotion SDK support"

This reverts commit 291c446c28fbe772b161cdb0246e1ebfef83ca84.
Revert "Revert "Add LeapMotion SDK support""

This reverts commit 8ce145085b3783782fafd051becbb0e339d5dfa1.
Support for LeapMotion and worklist 19734

-  Introduce the DeviceTracker class  to abstract all the possible
devices
- Introduce the MotionTracker ( a DeviceTracker ) that contains a
transform tree of joints
- Add Leapmotion class as a MotionTracker and the support for the
Leapmotion sdk in external
- Add InputController as the abstraction of a MotionTracker/Joint for
Javascript
Merge remote-tracking branch 'origin/LeapMotion' into 19734