Gzip support for static files

[Richard Macklin]

Hi, I see that static file support (#44) was added in 49fdcf3

puma-dev/README.md

Lines 168 to 170 in c5e86b4

 ### Static file support 
  
 Like pow, puma-dev support serving static files. If an app has a `public` directory, then any urls that match files within that directory are served. The static files have priority over the app. 

This works well, but I noticed that it doesn't seem to serve the gzipped version of static assets, akin to nginx's gzip_static directive or the gzip option of Rack::Static (rack/rack#863). Is this something puma-dev would like to support?

[Alan Norton]

Related to #87