Add API schema for v2.1 "update a server" API

Some v2.1 APIs(create/update/rebuild server) contains the API
extension feature, it searches extension methods with its method
name and operates them automatically.
It is necessary to change the API schemas also automatically based
on the API extension loading condition, because the API extensions
add API parameters.

This patch adds API schema extensions which are implemented with the
same mechanism (stevedore library) as the API extension for "update
a server" extensions.

Partially implements blueprint v3-api-schema

Change-Id: I2f80a994bc69153bd40251827aad0479876a94ab
Add API schema for v2.1 "rebuild a server" API

Some v2.1 APIs(create/update/rebuild server) contains the API
extension feature, it searches extension methods with its method
name and operates them automatically.
It is necessary to change the API schemas also automatically based
on the API extension loading condition, because the API extensions
add API parameters.

This patch adds API schema extensions which are implemented with the
same mechanism (stevedore library) as the API extension for "rebuild
a server" extensions.

Partially implements blueprint v3-api-schema

Change-Id: Ibfdd99966335d062cde4cc1d9ab3b63bc82ed0b6
Support image property for config drive

Currently Nova decides the config_drive based on user input and compute
node configuration. We should also consider the image requirement for
config drive.

Implements: blueprint config-drive-image-property

DocImpact:
    An new image metadata support added.

Change-Id: Ica32fb078d5440dbcf1251175585d34af9549815
Merge "Support image property for config drive"
Merge "Add API schema for v2.1 "update a server" API"
Merge "Add API schema for v2.1 "rebuild a server" API"