Decompress responses via`Content-Encoding` response header

[DonIsaac]

Support compressed responses when fetching webpages and scripts.

For webpages, decompression will probably happen in get_webpage when we check response headers.

keyhunter/src/walk/website/walk.rs

Line 288 in 0700469

if let Some(content_type) = response.header("Content-Type") {

It looks like the mainstream crate for compressing/decompressing steams is flate2 but other crates may be better.