Use oslo.rootwrap library instead of local copy

Remove rootwrap code copied from oslo-incubator, make the
ironic-rootwrap console_script entrypoint point to oslo.rootwrap
code instead.

Patch based on: https://review.openstack.org/#/c/67422

Change-Id: I3dd2c4cab6652dea5bd755b6048cbeea9edc81cf
Partial-Bug: #1268674
Add missing "Filters" section to the ironic-images.filters

The ironic-images.filters file is missing the [Filters] section. This
will cause the ironic-rootwrap command to fail.

Change-Id: I3780fc89e0144093a40035e6b91fcf946bbdf6a3
Partial-Bug: #1268674
Remove the absolute paths from ironic-deploy-helper.filters

The commands might be located in a different directories on different
distros, so this patch is removing the absolute paths in the
ironic-deploy-helper.filters file.

Change-Id: I68873a04acbf1519165f758b1803f12ba9ddf777
Closes-Bug: #1268696
Add [keystone_authtoken] to ironic.conf.sample

Update the auto-generation of our sample config file by exporting a
variable to oslo.config.generator such that it will include the
keystone_authtoken section when building our config.

Change-Id: I8f0d93846cd948059ac6cbc6ec4024257e2c3f27
Closes-bug: 1271308
Merge "Use oslo.rootwrap library instead of local copy"
Merge "Add missing "Filters" section to the ironic-images.filters"
Merge "Remove the absolute paths from ironic-deploy-helper.filters"
Merge "Add [keystone_authtoken] to ironic.conf.sample"