DEFER - CSD05 - Provide recognized values for tosca.nodes.compute properties: os_arch

TODO: we should declare what normative values we have or may use for interop. Portability is not guaranteed unless normative values exist.

Determine what other values we wish to make normative; suggested values include:

• power, s_390, z_arch, arm_32, arm_64
• IBM Z archs list:

Note: RHEL supports: x86, x86-64; Power Architecture; S/390; z/Architecture

IBM Z Archihtecture infor:
http://en.wikipedia.org/wiki/Z/Architecture

Power architecture info:
http://en.wikipedia.org/wiki/Power_Architecture