Port update method of cloudpipe_update to v2.1(v3)

This patch adds couldpipe_update's `update` method to cloudpipe controller
add validation schema to cloudpipe, have v2 unit test cases shared between
v2.1 and v2.

Partially implements blueprint v2-on-v3-api

Change-Id: Ibf39d7fa7301bcba6e259ae88a73c20f64b7fc36
Merge "Port update method of cloudpipe_update to v2.1(v3)"