refactor how Requests are ran

The Request class is not responsible for running itself anymore.
Its `run` methods (both class and instance) are gone.

The actual running of the request is handled by Connection in the
`run_request` method.

lib/faraday/connection.rb

@@ -187,12 +187,15 @@ def run_request(method, url, body, headers)
         raise ArgumentError, "unknown http method: #{method}"
       end
 
-      Request.run(self, method) do |req|
+      request = Request.create(method) do |req|
         req.url(url)                if url
         req.headers.update(headers) if headers
         req.body = body             if body
         yield req if block_given?
       end
+
+      env = request.to_env(self)
+      self.app.call(env)
     end
 
     # Takes a relative url for a request and combines it with the defaults

lib/faraday/request.rb

@@ -22,16 +22,18 @@ class Request < Struct.new(:path, :params, :headers, :body)
       :url_encoded => :UrlEncoded,
       :multipart   => :Multipart
 
-    def self.run(connection, request_method)
-      req = create
-      yield req if block_given?
-      req.run(connection, request_method)
+    attr_reader :method
+
+    def self.create(request_method)
+      new(request_method).tap do |request|
+        yield request if block_given?
+      end
     end
 
-    def self.create
-      req = new(nil, {}, {}, nil)
-      yield req if block_given?
-      req
+    def initialize(request_method)
+      @method = request_method
+      self.params = {}
+      self.headers = {}
     end
 
     def url(path, params = {})
@@ -63,22 +65,17 @@ def []=(key, value)
     #     :user       - Proxy server username
     #     :password   - Proxy server password
     # :ssl - Hash of options for configuring SSL requests.
-    def to_env_hash(connection, request_method)
+    def to_env(connection)
       env_params  = connection.params.merge(params)
       env_headers = connection.headers.merge(headers)
 
-      { :method           => request_method,
+      { :method           => method,
         :body             => body,
         :url              => connection.build_url(path, env_params),
         :request_headers  => env_headers,
         :parallel_manager => connection.parallel_manager,
         :request          => connection.options.merge(:proxy => connection.proxy),
         :ssl              => connection.ssl}
     end
-
-    def run(connection, request_method)
-      env = to_env_hash(connection, request_method)
-      connection.app.call(env)
-    end
   end
 end

test/env_test.rb

@@ -47,10 +47,10 @@ def test_request_create_stores_proxy_options
   end
 
   def env_for(connection)
-    env_setup = Faraday::Request.create do |req|
+    env_setup = Faraday::Request.create(:get) do |req|
       yield req
     end
-    env_setup.to_env_hash(connection, :get)
+    env_setup.to_env(connection)
   end
 end