Rewrite with android overflow support

[ptomasroos]

Now that overflow is supported in react-native both on android and ios we could use this to make the design more simplex.

This would also allow us to instead of having fixed width on the MultiSlider to actually move it into using the onLayout callback to get the size of where its been layouted and adapt according to regular style rules instead of having a fixed width as a calculation basis.

Hopefully this will allow us to reduce the absolute positioning which is used in order to hack around some of the constraints android had in previous life time.