Update md-whiteframe-z* to align with Material Elevation spec

[munaf-zz]

Currently, md-whiteframe-z* only supports 4 levels. The Material Spec includes 24.

Spec:
https://www.google.com/design/spec/what-is-material/elevation-shadows.html

Code sample from a Google Engineer working on Material:
http://codepen.io/shyndman/pen/MaYoaV

Additional request: can we use a class name that maps to the design spec, such as md-elevation-X or something similar?

[juanmiguelbesada]

We already have md-whiteframe-dp with 24 levels

https://github.com/angular/material/blob/master/src/components/whiteframe/whiteframe.scss

/close?

[jb29]

This should be added to the documentation.

[juanmiguelbesada]

It is already on master:

https://github.com/angular/material/blob/master/src/components/whiteframe/demoBasicUsage/index.html
https://material.angularjs.org/HEAD/#/demo/material.components.whiteframe

[EladBezalel]

closed with #4706