Fixes warnings, bad code and code style
Use the Z1 product ID as MAC/Node ID if no value is found in the XMEM
Merge pull request #824 from alignan/fix_warnings

Warning fixes
Merge pull request #820 from alignan/serialnum_as_nodeid

Use the Z1 product ID as MAC/Node ID if no value is found in XMEM
Merge branch 'master' of github:sieben/contiki