Adding support for negative x and y in layout xml.

Fixing default configurations for some screen sizes.

> Negative values for x and y are parsed as distance from end
column and row respectively. e.g.  (-1, -2) => (3, 2) in a
4x4 grid

Bug: 26110981
Change-Id: I4ca30e225ed6e2a31610ab23235d2cd10e8d317c