Enabled the ability to specify the parameter 'minEnergyThreshold' in springyui.js.
Also made the default value in springyui be very small, in order to cause the animation to end/stop smoothly.
Merge pull request #66 from Irrational86/springyui-minEnergyThreshold

Enabled the ability to specify the parameter 'minEnergyThreshold' in springyui.js