Hummingbird Compression

Adds request decompression and response compression to Hummingbird

Usage

let app = HBApplication()
// run response compression on application thread pool when buffer is 
// larger than 32768 bytes otherwise run it on the eventloop
app.addResponseCompression(execute: .onThreadPool(threshold: 32768))
// run request decompression on eventloop with no limit to the size
// of data that can be decompressed
app.addRequestDecompression(execute: .onEventLoop, limit: .none)

Adding request decompression means when a request comes in with header content-encoding set to gzip or deflate the server will attempt to decompress the request body. Adding response compression means when a request comes in with header accept-encoding set to gzip or deflate the server will compression the response body.