global: simplification of licensing

* Simplifies Workflow licensing to use more permissive Revised BSD
  License only.

* Renames the license file to more usual `LICENSE`.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>
Workflow v1.2.0

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>