Revise Stakeholders

[mmccool]

Update stakeholder definitions to address issues raised in #354.

• "System Maintainer" is also referenced three times but the links are broken. This however seems to be a typo in the reference URL, "Maintainter" instead of "Maintainer", easy to fix, and will be addressed in the PR to address issue Use Terminology Definitions for Stakeholders #366

The following issues were raised in the discussion for PR #354:

• A Gateway that is WoT aware is always a Consumer, or related
• Device Owner/System Owner and Device User/System User are related
• The entity writing or designing a TD, which may be a human or an automated system, e.g. a conversion tool. How about "TD Creator"?
• The entity programming the Consumer application ("Consumer Creator"?)
• More careful definition of "Providers", can be "Service Provider" which could include "Web Service Provider" or "Network Service Provider"
• Identity Provider should be Identity Service Provider to make hierarchy clearer
• Maybe missing Implementor, Tooling (TD Writer covered by TD Creator, above, Implementor maybe coverded by Consumer Creator, but maybe not, there may be implementors of Directory Services, etc. too)

[mmccool]

I have made a list of the points I saw discussed in PR #354, if I missed anything please note it below. After we resolve #366 then we can fix up the Stakeholder definitions to address these points.

[mmccool]

Waiting for Issue #366 to be resolved, then I will make a PR to resolve the above content issues.

[mmccool]

Some other proposed terms were raised in a now-closed issue: network systems vs. IoT systems