Make sure easing curves and shadows are on-spec

[jelbourn]

Current easing curves and shadows are pulled from Angular 1 version. We need to double check that these reflect the current state of the spec.

[bakgat]

In _shadows.scss this link is provided as documentation for shadows
http://google.com/design/spec/what-is-material/objects-in-3d-space.html

In the new spec the link should be http://www.google.com/design/spec/what-is-material/elevation-shadows.html

I think there are differences in shadows.
eg For raised buttons it states 2dp elevation, 8dp on active.

[traviskaufman]

mdElevation Design Doc: https://docs.google.com/document/d/1W3NGSLqDZzjbBBLW2C6y_6NUxtvdZAVaJvg58LY3Q0E/edit?usp=sharing