Fix dependency issues, rename numrows and make function errors more obvious

[jlane9]

Changes

• Return 400 error response for generate data exceptions
  • Making it so that data generation errors are obvious to the user
• Rename query param numrows to num_rows
  • numrows query param did not match num_rows schema property
• Add list and tuple to approved globals
  • Seemed like an obvious addition
• Add mongo URI and SSL
• Add dnspython as a dependency
  • These two were required to get connections to managed mongo resource
• Hard code werkzeug to 0.15.4
  • Fixes #18 Suggestion from @NeolithEra to hardcode werkzeug to prevent version conflicts