oq_reset_db: several improvements
oq_reset_db: several improvements

- Short flags added
- Verbose mode added
- The script can run even if oq_create_db is not in PATH but in the same folder
- Better output


Former-commit-id: 998855fdf4539ffdf92697200173a1056a89c2ca [formerly 888f198d1e80e2b22d39e8f32222f607d74a9a10]
Former-commit-id: 82514d72e3dcad20f5dcc206db3b93ca214eb5e0
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine