Moved ThreadedTest to testutils. Also, added commentary to the test.

This resolves hangs of the unit tests on some systems.

 - Remaining methods renamed
 - comments expanded
 - size() > 0 replaced with !empty() checks.

 - added extra explanations
 - code no longer uses inefficient size() > 0

    Merge branch '101-cb-add-two-step-configuration-to-the-dhcpv4-server-3'

# Conflicts:
#	src/bin/netconf/tests/netconf_tests.sh.in

 - mostly moved to wiki, also cleaned up some text