Beginnings of a docker plugin.

Scan for content of appropriate type, and identify the cert and key paths we
need to copy in for docker.
Docker plugin now copying certs and cleaning out old ones.

Unknown files should be left alone, CA certificates for one example.
Anything ending with .cert or .key however is fair game for removal.
Update spec and makefile for docker plugin.

Conflicts:
	subscription-manager.spec
Hook up docker plugin.
Hook up a configured hostname sub-dir for docker certs.
Rename to generic container content plugin.

Trademark issues.
Add container plugin update report.
Add a more thorough test.
Simplify container content plugin to it's own module.
Complete a test, and move to correct location.
Stylish updates.
Update spec and makefiles.
Case insensitive content type searching.
Test container content keypair equals method.
Assume /etc/docker/certs.d is owned by another package.
Copy cert/key mode to match their source files in /etc/pki/entitlement.
Support multiple container cert directories.

Due to redirects, docker will need to communicate with both a crane host, and
then the CDN.
Fix cert/key filenames for container plugin.

Base filename should match, so stop naming them SERIAL-key.key and instead just
SERIAL.key.
Symlink to redhat-uep.pem if we seem to be syncing a CDN hostname cert dir.

The CDN CA cert is required if we're going to communicate with cdn.redhat.com
or cdn.stage.redhat.com. We decided to watch for hostnames like these in the
plugin, and if spotted we'll make sure there's a symlink to
/etc/rhsm/ca/redhat-uep.pem, assuming it exists.
Code cleanup.