Remove nose and add pytest
Remove nose and add pytest


Former-commit-id: f199b25422f5f98ee1555e8817b5962b522792d9 [formerly 221e97f258fbd2c657a5b1378a4634ef224d65d9] [formerly 221e97f258fbd2c657a5b1378a4634ef224d65d9 [formerly c9ee4a67fcdc47ab7a470257931a3ec29377b56c]]
Former-commit-id: a9481bcf92811efa5df972285cbf8a1af408222b
Former-commit-id: e624db16043c139b5ac621a81b66c7ac7ef5c7ea
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine