noUiSlider fix

[lionel-bijaoui]

Fix some problem described in #71 and add some enhancement:

• to help style the field, some class are applied dynamically (for pips and tooltips)
• schema is updated along with data to generate income data and to uncomment rangeSlider (I accidentally commented it in a previous update)
• a small change on a condition to avoid "undefined value" warning

A unit test was deactivated since I was not able to trigger a change in model. 😞
I don't know how to simulate a click somewhere on the range slider or have it ready to use.
I give up for now, since the field clearly work as expected anyway. It represent too much work for me right now. Hope that's ok.

[icebob]

Thanks. But I create an issue with this skipped test, that we don't forget it.

[lionel-bijaoui]

Thank you, I was about to create the issue ! :)