Add pre and check phases to test migration 006

Assure the column name changed and the data is accessible on it.

Change-Id: I1befe31a2c37fd5a27833cf2d41dfb5a57190c39
Cannot change locations on immutable images

This change extends immutability to the contents of image locations.

Change-Id: I5bfe9b73733eb92e0d27bd0222f6ad1a89ce5d78
Update documentation to reflect API v2 image sharing

Related to bp glance-api-v2-image-sharing

Change-Id: Ida2f530ef2c8474ec29f8870c2218c291a9e449c
Merge "Cannot change locations on immutable images"
Merge "Add pre and check phases to test migration 006"
Merge "Update documentation to reflect API v2 image sharing"