add SetCookieJar method to override default CookieJar (#69)

client.go

@@ -150,6 +150,17 @@ func (c *Client) SetHeaders(headers map[string]string) *Client {
 	return c
 }
 
+// SetCookieJar method sets custom http.CookieJar in the resty client. Its way to override default.
+// Example: sometimes we don't want to save cookies in api contacting, we can remove the default
+// CookieJar in resty client.
+//
+//		resty.SetCookieJar(nil)
+//
+func (c *Client) SetCookieJar(jar http.CookieJar) *Client {
+	c.httpClient.Jar = jar
+	return c
+}
+
 // SetCookie method sets a single cookie in the client instance.
 // These cookies will be added to all the request raised from this client instance.
 // 		resty.SetCookie(&http.Cookie{

client_test.go

@@ -220,6 +220,17 @@ func TestSetScheme(t *testing.T) {
 	assertEqual(t, true, DefaultClient.scheme == "http")
 }
 
+func TestSetCookieJar(t *testing.T) {
+	DefaultClient = dc()
+	backupJar := DefaultClient.httpClient.Jar
+
+	SetCookieJar(nil)
+	assertEqual(t, true, DefaultClient.httpClient.Jar == nil)
+
+	SetCookieJar(backupJar)
+	assertEqual(t, true, DefaultClient.httpClient.Jar == backupJar)
+}
+
 func TestClientOptions(t *testing.T) {
 	SetHTTPMode().SetContentLength(true)
 	assertEqual(t, Mode(), "http")

default.go

@@ -89,6 +89,11 @@ func SetHeaders(headers map[string]string) *Client {
 	return DefaultClient.SetHeaders(headers)
 }
 
+// SetCookieJar sets custom http.CookieJar. See `Client.SetCookieJar` for more information.
+func SetCookieJar(jar http.CookieJar) *Client {
+	return DefaultClient.SetCookieJar(jar)
+}
+
 // SetCookie sets single cookie object. See `Client.SetCookie` for more information.
 func SetCookie(hc *http.Cookie) *Client {
 	return DefaultClient.SetCookie(hc)