**Is your feature request related to a problem? Please describe.**
It's frustrating there's no option to turn off decompress. There are situations where you want to do this. Ex: having a service that collects data, but doesn't analyze it. which then passes to another service immediately/eventually.

While data is waiting or in traffic to next stop, it should stay compressed. The difference in byte size is huge (for me, 60MB vs 1-2MB). 

**Describe the solution you'd like**
Add an option to the request to not automatically decompress for me. I'm a big boy, I can handle it myself later.

**Describe alternatives you've considered**
There are none except user another lib or write own http req (which is ridiculous just to turn off a auto feature).


I can submit a PR if no one else wants to do it (it's not hard to add). But let me know how you'd like the option to be passed in? An extra options key? `axios({ url: ..., method: ..., decompress: false })` , or adding option to an existing option?


test/unit/adapters/http.js
axios.get('http://localhost:4444/', {
          proxy: {
            host: 'localhost',
            port: 4000
          }
        }).then(function (res) {
          assert.equal(res.data, '123456789', 'should pass through proxy');
          done();
        });
      });
    });
  });
  it('should not pass through disabled proxy', function (done) {
    // s
    process.env.http_proxy = 'http://does-not-exists.example.com:4242/';
    server = http.createServer(function (req, res) {
      res.setHeader('Content-Type', 'text/html; charset=UTF-8');
      res.end('123456789');
    }).listen(4444, function () {
      axios.get('http://localhost:4444/', {
        proxy: false
      }).then(function (res) {
        assert.equal(res.data, '123456789', 'should not pass through proxy');
        done();
      });
    });
  });
  it('should support proxy set via env var', function (done) {
    server = http.createServer(function (req, res) {
      res.setHeader('Content-Type', 'text/html; charset=UTF-8');