This patch adds the code to collect the deployment logs from the IPA
ramdisk. The logs can be collect for every deployment, upon a failure or
never. By default, logs are collected upon a failure.
After collection, logs can be storaged either in the local filesystem
(default) or in Swift.
If an error occurs when the logs are being collected, storaged or if the
ramdisk does not support the collect_system_logs command Ironic will log
an error message, but the deployment will proceed.
Documentation on how to enable and other configuration will be done on a
subsequent patch.
Partial-Bug: #1587143
Change-Id: I6da1110daa94ea25670f71f9862e51cc9bbc6f93