Agreed on this change on Jabber.

The former replaces the -v with the -d parameter in D2 unit tests. This
enables the D2 tests that were skipped when the -v parameter was in use.
The -v causes D2 to print version number and exits. The other patch is
for printing configuration summary in D2 which we were not aware was failing
because tests used to be skipped with -v parameter.

This was also suggested in the review.

Also, added documentation to the Host class.