Adding option to disable automatic decompression (#2661)

* Adding ability to disable auto decompression

* Updating decompress documentation in README

* Fixing test\unit\adapters\http.js lint errors

* Adding test for disabling auto decompression

* Removing changes that fixed lint errors in tests

* Removing formating change to unit test

Co-authored-by: Xianming Zhong <chinesedfan@qq.com>

README.md

@@ -410,7 +410,14 @@ These are the available config options for making requests. Only the `url` is re
   // `cancelToken` specifies a cancel token that can be used to cancel the request
   // (see Cancellation section below for details)
   cancelToken: new CancelToken(function (cancel) {
-  })
+  }),
+
+  // `decompress` indicates whether or not the response body should be decompressed 
+  // automatically. If set to `true` will also remove the 'content-encoding' header 
+  // from the responses objects of all decompressed responses
+  // - Node only (XHR cannot turn off decompression)
+  decompress: true // default
+
 }
 ```