Multiple handles support for Slider

[soundar24]

Currently the default slider support support single handle only. Here need to provide option to add / remove additional handles with the slider. [Note: If possible we can consider this for min-range sliders also]

Same requirement from Stack overflow: http://stackoverflow.com/questions/28408445/jquery-knob-is-it-possible-to-have-a-range/31817074#31817074 Workaround: http://jsfiddle.net/soundar24/utqgufx0/6/

Some references: http://vanderlee.github.io/limitslider/

[soundar24]

Also requested from here: http://roundsliderui.com/#comment-2893586773