rest: Add RemoveHeader and SetCookie method

These methods extend the rest package to support the cookie header and
header deletion.

The deletion is necessary to delete an existing authorization header if
cookie auth should be used.

lib/rest/rest.go

@@ -80,6 +80,14 @@ func (api *Client) SetHeader(key, value string) *Client {
 	return api
 }
 
+// RemoveHeader unsets a header for all requests
+func (api *Client) RemoveHeader(key string) *Client {
+	api.mu.Lock()
+	defer api.mu.Unlock()
+	delete(api.headers, key)
+	return api
+}
+
 // SignerFn is used to sign an outgoing request
 type SignerFn func(*http.Request) error
 
@@ -100,6 +108,19 @@ func (api *Client) SetUserPass(UserName, Password string) *Client {
 	return api
 }
 
+// SetCookie creates an Cookies Header for all requests with the supplied
+// cookies passed in.
+// All cookies have to be supplied at once, all cookies will be overwritten
+// on a new call to the method
+func (api *Client) SetCookie(cks ...*http.Cookie) *Client {
+	req, _ := http.NewRequest("GET", "http://example.com", nil)
+	for _, ck := range cks {
+		req.AddCookie(ck)
+	}
+	api.SetHeader("Cookie", req.Header.Get("Cookie"))
+	return api
+}
+
 // Opts contains parameters for Call, CallJSON etc
 type Opts struct {
 	Method                string // GET, POST etc