Add mimetype for webassembly
Add mimetype for webassembly

This adds a media type for webassembly modules.

According to this part of the [WebAssembly standard](https://www.w3.org/TR/wasm-web-api-1/#streaming-modules), web browsers must reject the compilation of webassembly modules that don't have the correct mimetype, so it's pretty critical for applications serving .wasm.
evansd/whitenoise,evansd/whitenoise,evansd/whitenoise