Add version support to schema and spec

This blueprint is for adding version support to schema and spec. This function is for keeping backward compatible for policies and profiles with different versions.

Basic ideas:
1. Each property has support version scope specified using 'min_version' and 'max_version';
2. User specifies spec version by defining 'version' field in spec file as usual;
3. When creating profile/policy, spec validation method will check the available version scope of each property schema defined in profile/policy plugin and check whether spec version is in that scope. If not, that means user defines a property that is not supported in given version plugin. In this case, exception will be raised to fail the profile/policy creation and warning message will be sent back to user.