Add demos/clj-frontend and change some names

In addition to adding a demo, this commit also modifies clj-frontend by
changing the workflow function to new-workflow and changing the function
input parse-tree to w-flow.  Changing parse-tree to w-flow seems to
better hide the implementation details of a workflow from users.
Delete LICENSE from demos/clj-frontend
Merge pull request #125 from morrifeldman/clj-frontend/doc

Add demos/clj-frontend and change some names