Feature Request: Caching settings

[janreges]

This task has 2 parts:

1. Add a summary analysis of HTTP cache settings for different content types (HTML, Image, Font, etc.) and based on Content-Type. Either as a separate section, or add columns Avg cache | Min cache | Max Cache to the Content types section, with avg/min/max cache-lifetime information found for the content type.
2. Add a Cache column to Visited URLs, where the cache-lifetime will be enabled with highlighting based on content type (disabled cache is fine for HTML, but not usually for assets).