Fix links in README.md for release 2.0
Fix links in README.md for release 2.0

vup1120/oq-hazardlib,gem/oq-engine,gem/oq-engine,vup1120/oq-hazardlib,gem/oq-hazardlib,rcgee/oq-hazardlib,gem/oq-engine,gem/oq-engine,gem/oq-engine,vup1120/oq-hazardlib,gem/oq-hazardlib,rcgee/oq-hazardlib,gem/oq-hazardlib