send errors to stderr
fix missing requirements

a minimal centos install may not have either wget or dbus, both of which
are required for these scripts to complete successfully.
set up ssh authentication

packstack relies on functioning ssh access to the local system but
doesn't seem to be able to set it up correctly.  these changes create
ssh keys for root if none exist and then add the public key to
authorized_keys for root.
make sure authorized_keys has mode 600

also move path names to variables rather than typing them
over and over and over.
delete instances after test

when testing with constrained memory, deleting an instance
after a successful test leaves more resources available
for the following test.
Revert "delete instances after test"

Hmm, okay, that won't work.  I see that we want the grizzly instance
still running after upgrading to Havana.  I'll just try more memory
instead.

This reverts commit 48b23f562f199d001a90b58eaa9768b7d8e3c1b6.
Merge pull request #1 from larsks/master

Make test_rdo_upgrade run from a minimal CentOS install (and fix some packstack annoyances)