Change implementation of drawer pattern

[paulcpederson]

Having the drawer push the wrapper over creates several problems (on mobile safari, and in preventing the use of position: sticky elsewhere on the page.

Should change so that the drawer slides over the wrapper. Make the following changes:

1. remove transitions on wrapper
2. remove overflow: hidden declaration on wrapper
3. when drawer opens, add overflow: hidden to html element (this prevents scrolling in background)

[paulcpederson]

will be part of next release

[asangma]