Fixed database cleanup for CsvModelLoaderDBTestCase.
Fixed database cleanup for CsvModelLoaderDBTestCase.

Performs the cleanup both before and after the test and use
a separate user with DELETE grant.


Former-commit-id: b4c1eb064f628d5014ded4038e090c4d71ba9c38 [formerly e4341e46991e0d5dfe63054bd8df27ddd1c78dc8]
Former-commit-id: 7f8c02e531c1fa41e6e09c697c8027021c91ca4c
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine