Correct bug detecting content type and parsing json responses

This is likely a breaking bug fix, since requests will now _correctly_ parse the response body as json and return a hash, instead of returning the body as a string.

Fixes fog#34

lib/fog/aliyun/compute.rb

@@ -300,13 +300,18 @@ def reload
 
         def request(params)
           begin
-            response = @connection.request(params.merge(headers: {
+            headers = {
               'Content-Type' => 'application/json',
               'Accept' => 'application/json',
               'X-Auth-Token' => @auth_token
-            }.merge!(params[:headers] || {}),
-                                                        path: "#{@path}/#{params[:path]}",
-                                                        query: params[:query]))
+            }.merge!(params[:headers] || {})
+
+            request_params = params.merge(
+              headers: headers,
+              path: "#{@path}/#{params[:path]}",
+              query: params[:query])
+
+            response = @connection.request(request_params)
           rescue Excon::Errors::HTTPStatusError => error
             raise case error
                   when Excon::Errors::NotFound
@@ -316,7 +321,7 @@ def request(params)
                   end
           end
 
-          response.body = Fog::JSON.decode(response.body) if !response.body.empty? && response.get_header('Content-Type') == 'application/json'
+          response.body = Fog::JSON.decode(response.body) if !response.body.empty? && response.get_header('Content-Type').start_with?('application/json')
 
           response
         end

lib/fog/aliyun/models/compute/servers.rb

@@ -10,7 +10,7 @@ class Servers < Fog::Collection
         model Fog::Compute::Aliyun::Server
 
         def all(options = {})
-          Fog::JSON.decode(service.list_servers(options).body)['Instances']['Instance']
+          service.list_servers(options).body['Instances']['Instance']
         end
 
         # Creates a new server and populates ssh keys