Fix regression in non-admin simple_usage:show.

Commit 6ff32210772a67a1b526d9d784030afc90f3ce99 optimized the db query
for usage but replaced a call that had require_context with one that
had require_admin_context. This causes usage show to throw a 403. We
check for admin_or_owner in policy, so there is no need to check for
admin context at the db layer.

Fixes bug 1122267

Change-Id: Iff362f46d83a710f3883538bcb646e3457e0ba64
Fix passing conductor to get_instance_nw_info()

The recent metadata patch missed this one spot, which wasn't caught
because the network stubs weren't updated for the signature change.

Fixes bug 1123435

Change-Id: Iebeb98bba62189476af2c0b85615ea407a8b2ecd
Merge "Fix passing conductor to get_instance_nw_info()"
Merge "Fix regression in non-admin simple_usage:show."