re-wrote get_source_models using lxml instead of the java parser
re-wrote get_source_models using lxml instead of the java parser

instantiating the jvm prior to an os.fork() is a big no-no


Former-commit-id: 73fc81412eec0b72492b768e5e1e7eca0c5a06d5 [formerly ccdf09504e4236e2ed17b31d8d2204eaf8bf3b80]
Former-commit-id: ff53331455971d03796e21f01c8ed7aa75ad194f
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine