Update to Atmel LWM version 1.1.1

This imports (part of) the code from the "Lightweight Mesh Software
Stack v1.1.1" zipfile, as downloaded from the [atmel website][1].

There are no really relevant changes since 1.1.0, most of the changes
are probably in the part of the code that is not imported.

[1]: http://www.atmel.com/tools/lightweight_mesh.aspx
Merge branch 'upstream'