Add options to use remove_unused_* parameters

Being able to modify the parameters "remove_unused_base_images",
"remove_unused_original_minimum_age_seconds",
"remove_unused_kernels", "remove_unused_resized_minimum_age_seconds"
if desired.

Change-Id: Ia24594ccc4b999674456e59a279e2d5916cd5d7a
Implements: blueprint add-remove-unused-parameters
Merge "Add options to use remove_unused_* parameters"
Removed references to ML2 plugin.

The plugin description was left over from the template this was built from.

Change-Id: I1fb1cfa1cc70648cdc661c650015ecfeba77eccf
add parameter for endpoint protocols

This gives the ability to specify https endpoint for
internal and/or admin endpoints.

Change-Id: I5f936593f83ce8f00338709e5864f7d00f9d0d8c
backport: havana
Merge "Removed references to ML2 plugin."