Convert service v3 plugin to v2.1 API

Changes required to have v3 plugin natively support the V2.1
API

Remove the 1st level dict of service in the body param

Partially implements blueprint v2-on-v3-api
Co-Authored-by: Chris Yeoh <cyeoh@au1.ibm.com>
Change-Id: Ida59f00e3cf4640b63add1d6350aa7c30529807e
Merge "Convert service v3 plugin to v2.1 API"