Feature - Add a vertical option to display vertical sliders.

Improvement - force labels to stay contained within element containing slider. Closes #182. Thanks to @karelcallens for it.

Closes #180

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Refactor to add an rzSliderOptions attribute

As reported in #174

As explained in #172 .

As discussed in #161

This is to ease to use of non linear/number steps. As suggested in #163

As mentioned in #162

Implement the solution described in #159 .

Refactor the slider architecture. Add a rzSliderOptions that handle all the options except model, high and rzSliderTplUrl