[md-layout] A small suggestion for improvement

[Elvanos]

After tinkering with the layout of this awesome pack, I realized that the layout system is missing one relatively important feature of Flex display.

Issue:

The layout module doesn't allow for auto-scaling the width of the md-layout-item elements based on the width of their own content.

Solution:

I propose adding the following code to the Layout module:

.md-layout-item.md-size-auto{
  flex-grow: 0;
  flex-shrink: 1;
}