Mime type mismatch false positives on extensionless uris

[lisaSW]

Problem

URIs with no file extension were flagged as MIME type mismatches since an empty extension never matches any of the valid extensions for the responding MIME type.

Changes

• The mime_type_uris view now skips URIs that have no extension
• Includes Fix for wrong mime type mismatch detection #96 which improves extension matching for MIME types that have more than one valid extension

Tests

• Updated the extensionless mismatch test cases to have no successful matches
• Updated the proxy rolling threat counts for the removed modifier rows