Adds v3 API samples for limits and simple tenant usage

Adds the v3 API samples for the limits and simple tenant
usage extensions. Bundled together to reduce review load

Partially implements blueprint v3-api-specification

+DocImpact

Change-Id: I1b73d7acf8d1bbccec2fff6180799edd3f3b12aa
Merge "Adds v3 API samples for limits and simple tenant usage"