Fix the webdists, this fixes #170.

Particular problems and how they were resolved:
 - The `fs-extra` module, used exclusively by TokenCacher, didn't have a browser version. I rewrote TokenCacher to not use fs-extra (see fdd4cfc7cc)
 - TokenCacher wouldn't work in the browser anyway due to lack of a file system. I made a shim (`Util/TokenCacher-shim.js`) that implements all TokenCacher functionality as null implementations, this causes `login` to always make a request.
 - Compressed packets couldn't be parsed because neither node's Buffers nor zlib were working correctly. Initially I tried to make a browser-only parser class that parses compressed `Blob` packets, but this didn't work out, so I just disabled compression by default.

package.json

@@ -44,5 +44,9 @@
   },
   "engines": {
     "node": ">=0.12.7"
+  },
+  "browser": {
+    "./src/Util/TokenCacher.js": "./src/Util/TokenCacher-shim.js",
+    "./lib/Util/TokenCacher.js": "./lib/Util/TokenCacher-shim.js"
   }
 }