Allow .teuthology.yaml to set downburst path

If .teuthology.yaml defines downburst, _get_downburst_exec()
now returns that value as the path to the downburst executable.

Also cleaned up code in create_if_vm.  ctx.downburst_conf was
never defined, so the code that handled the AttributeError
was always being executed.

Fixes: 6921

Signed-off-by: Warren Usui <warren.usui@inktank.com>
Revert "Revert "Show hostname instead of IP in errors""

This reverts commit 10fee0e368750cf4cd953db5700df59c7f611119.

Conflicts:
	teuthology/orchestra/run.py
Use Unicode format strings

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Consolidate log file setup into shared function

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Use Remote.hostname in logs

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Add Remote.ensure_online()

If the connection is alive, do nothing. If not, reconnect. Allow any
exceptions to bubble up to the caller. This is intended to fix unhelpful
'Bad File Descriptor' errors we were seeing when VMs go down.

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Use 'true' instead of 'echo online'

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Pass hostname to execute()

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Fix PEP-8 issues

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Remote.hostname doesn't have to be a property

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Make Remote.shortname actually short

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Use Remote.shortname in logs

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Add Remote.user attribute

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Use Remote.user

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Express hostnames as child logger names

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Catch any Unicode errors that manage to sneak in

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Use 'stderr' and 'stdout' as logger names

We were using just 'err' and 'out', which isn't very intuitive.

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Don't pass a custom logger anymore

We already use the hostname in command execution calls

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Merge pull request #255 from ceph/wip-6921-wusui

Allow .teuthology.yaml to set downburst path
Fix name parsing

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>