Fix encoding buffer to support browsers

Normally msgpack-javascript should work out of the box as the output of encode is Uint8array but due to this issue we have to initialise it again as the buffer is missing Ref msgpack/msgpack-javascript#145

src/encoder.js

@@ -8,7 +8,7 @@ const buildEncoder = (options = {}) => {
 
         encode(packet) {
             const encoded = msgpack.encode(packet, this.options);
-            const buffer = Buffer.from(encoded);
+            const buffer = new Uint8Array(encoded);
 
             return [buffer];
         }