LWP::UserAgent::Cached - LWP::UserAgent with simple caching mechanism

When you process content from some website, you will get page one by one and extract some data from this page with regexp,
DOM parser or smth else. Sometimes we makes errors in our data extractors and realize this only when all 1_000_000 pages 
were processed. We should fix our extraction logic and start all process from the begin. Please STOP! How about cache? 
Yes, you can cache all responses and second, third and other attempts will be very fast. LWP::UserAgent::Cached is yet 
another LWP::UserAgent subclass with cache support. It stores cache in the files on local filesystem and if response 
already available in the cache returns it instead of making HTTP response.
