Summary: nothing to see here, move along

Fix for a stupid mistake.
Summary: Make canHandle protected

Change access to canHandle so it's easier to unittest. 

Make a note that answers can be null if the host is down, there should
be a way to deal with this, but for now an NPE is an adequate indication
that something is wrong.
Summary: Small fixes for issues found during unittests
Summary: Unittest for nicira plugin

More unittests for the Guru

Add unittests for the Element
Summary: Remove useless and commented code