Define a Schema format for properties

Define a Schema class for properties and their constraints that is easily
serialisable to a JSON schema format that matches the proposed Parameter
input syntax for HOT. Since resource properties have not been exposed to
the user before, this format will make the most sense to a user in the long
term.

A future patch will switch the Property validation code over to using
Schema objects instead of the dictionary-based schemata currently in use.

blueprint resource-properties-schema

Change-Id: I79fa5927bdffeaf103a1c2ba58b709b4ba72b551
Tidy up RPC API definitions

Ensure that the layouts of names and values match.

Change-Id: I8cea3dc7ea1fd2a1b722ddd7058564d5195b738b
Merge "Define a Schema format for properties"
Merge "Tidy up RPC API definitions"