Refactor ManageImageBinaries (was ImageBinariesRequest)

 * Pixels are no longer deleted but are toggled to `_bak`
 * "archived" is used rather than "attached"
Test cleanup after refactoring
Add null check to requireFileset
Add --extended option to 'fs archived'
Renamed 'fs archived' to 'fs images'

This makes the `ManageImageBinaries` command more
generally useful since it can provide details on
other pre- and post-FS data. No modification ops
are made available via the CLI yet.
Remove extra slash from repos
Print ERR if MIB is not available