Deployment: check production settings

[ar-jan]

• [x] Use immutable mode for added performance/security
• [x] Use --inspect-file for performance
• [x] Check settings for download option
• [x] Allow/Disallow custom user queries? (no need to disallow)
• [x] Check presence/use of relevant indexes
• [x] Use default_cache_ttl
• [x] Use num_sql_threads
• [x] Use gunicorn (#30)

[ar-jan]

Performance looks fine, but declaring collate nocase in the index may be faster than using it (only) directly in the query.

Edit: used collate nocase for the relevant colums, hence indexes as well.

[ar-jan]

Added default_cache_ttl, num_sql_threads settings.