Create OAuth2 use case

A place to capture use cases for OAuth2 flows.
These should carefully read the actual OAuth2 specifications.
See w3c/wot-scripting-api#214 for discussion.

USE-CASES/oauth.md

@@ -0,0 +1,87 @@
+## Title: OAuth2 Flows
+
+### Submitter(s): 
+
+Michael McCool
+
+### Reviewer(s):
+
+<Suggest reviewers>
+
+### Tracker Issue ID:
+
+<please leave blank>
+
+### Category:
+
+<please leave blank>
+
+### Class: 
+
+<please leave blank>
+
+### Status: 
+
+WIP
+
+### Target Users
+
+<List all stakeholders that are involved in the use case from the following list:
+- device owners
+- device user
+- cloud provider
+- service provider
+- device manufacturer
+- gateway manufacturer
+- network operator (potentially transparent for WoT use cases)
+- identity provider
+- directory service operator>
+
+### Motivation:
+
+For each OAuth2 flow, we need to define a use case for which it is relevant.
+
+### Expected Devices:
+
+<List the target devices, e.g. as a sensor, solar panel, air conditioner>
+
+### Expected Data:
+
+<List the type of expected data, e.g. weather and climate data, medical conditions, machine sensors, vehicle data>
+
+### Dependencies - Affected WoT deliverables and/or work items:
+
+<List the affected WoT deliverables that have to be changed to enable this use case>
+
+### Description:
+
+<Provide a description from the users perspective>
+
+#### Variants:
+
+For each OAuth2 flow, there is a corresponding use case variant.
+We also include the experimental "device" flow for consideration.
+
+* code
+* implicit
+...
+* device
+
+### Security Considerations:
+
+<Describe any issues related to security; if there are none, say "none" and justify>
+
+### Privacy Considerations:
+
+<Describe any issues related to privacy; if there are none, say "none" and justify>
+
+### Gaps:
+
+<Describe any gaps that are not addressed in the current WoT standards and building blocks>
+
+### Existing standards:
+
+<Provide links to relevant standards that are relevant for this use case>
+
+### Comments:
+