[ogsa-wg] use case template

Re our workflow use case discussion of 3/14 am http://forge.ogf.org/sf/docman/do/downloadDocument/projects.ogsa-wg/docman.r... Here's the template I propose for use cases: Title Keywords Goal and description Actors/stakeholders Assumptions Preconditions Main flow of events (Basic, alternate, exceptional) Postconditions Success requirements Special Requirements Issues Sources/references OGF sponsor/stakeholder/interested party