deflateAssertion = function () {
        confirmCompression.call(this, 'deflate');
    }
Checks that the response is deflate compressed
    @alias module:chakram-expectation.deflate
    @example 
    it("should detect deflate compression", function () {
        var deflate = chakram.get("http://httpbin.org/deflate");
        return expect(deflate).to.be.encoded.with.deflate;
    });