virt: More verbose port redirect exception message

Include more details about the NIC and Network in question when
reporting possible port-redirection problems.  Sample:

14:57:16 DEBUG| Destroying VM
14:57:16 DEBUG| Trying to shutdown VM with shell command
14:57:16 DEBUG| Don't know how to connect to guest port 22 with
                networking type 'user', to destination 'virbr0',
                for nic 'nic1' with mac '52:54:00:5d:5e:5f' and
                ip 'None'.

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: Override default nettype based on uid

When test runner is executed as root, default to using bridge-mode
networking.  Otherwise, force it to user-mode, unless different
on the command line.

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: Warn if uid==0 and nettype==user

Sample output:

15:37:08 INFO | Starting test ...
15:37:08 DEBUG| Test parameters:
                     ...
15:39:52 WARNI|
15:39:52 WARNI| Testing with nettype='user' while running as root may
                produce unexpected results!!!
15:39:52 WARNI|

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: Change default nettype to 'user' in config

This change mirrors the default as used by the test runner.  I
added/rearranged the comments to make it clear it will be overridden.

Signed-off-by: Chris Evich <cevich@redhat.com>
virt: rv_build_install spelling fix

Signed-off-by: Chris Evich <cevich@redhat.com>
Merge pull request #1026 from cevich/nettype_user_default

Nettype user default fixes