Add license file.
Add license file.


Former-commit-id: 71eec55c05f57b2ed2ce8df7374ffaa5bd8849cd [formerly 40f77eec036702f94a63e01e378519bc5347a705]
Former-commit-id: 1faa46bcbe1bf9c11186aed145147d8e443f61c9
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine