Advisory capabilities shouldn't have required_since value set, it
will be set once they get moved to required.
The following 2 capabilities were defined, however, they weren't
aded anywhere (required, advisory, ...):
* images-v2-import
* objectstore-account-update
This commits adds them to the advisory.
Change-Id: I32b5175b1053f97238284ceab10594cc42c4ad16
a47a31b443