Fixed #412
Fix for #413
Added SplinePositionInterpolator.js to the Inerpolation Component.
Added SplinePositionInterpolator to packages.
Modified sanity check for SplinePositionInterpolator node.
Fixed closed loop interpolation when key velocities are unspecified.
Merge branch 'spline_pos_interp' of https://github.com/ankit1089/x3dom into spline_pos_interp

Conflicts:
	src/nodes/Interpolation/SplinePositionInterpolator.js