Add imgtool fix for new backend

[IsaacKhor]

• Remove rados backend option
• Change pool to be an explicit option

[IsaacKhor]

@knikolla added the image create, but we should add tests for all the code paths in a script somewhere and run that instead

Probably merge in thick-image (which just provisions all the objects up-front) into imgtool too

[knikolla]

@knikolla added the image create, but we should add tests for all the code paths in a script somewhere and run that instead

Probably merge in thick-image (which just provisions all the objects up-front) into imgtool too

@IsaacKhor Totally. For now this is merely a way to test that the issue which this PR is meant to fix (context creation) is actually fixed and to avoid the regression of this particular one issue.

One a different note, we should really make the keyring name and ceph.conf location customizable.

[knikolla]

Looks good to me.