don't use ReadAll when decoding JSON

An empty stream isn't valid JSON, so we shouldn't silently ignore it.

utils.go

@@ -1,29 +1,11 @@
 package jira
 
 import (
-	"encoding/json"
 	"fmt"
-	"io"
-	"io/ioutil"
 	"net/url"
 	"path"
 )
 
-func readJSON(input io.Reader, data interface{}) error {
-	content, err := ioutil.ReadAll(input)
-	if err != nil {
-		return err
-	}
-	if len(content) == 0 {
-		return nil
-	}
-	err = json.Unmarshal(content, data)
-	if err != nil {
-		return fmt.Errorf("JSON Parse Error: %s from %q", err, content)
-	}
-	return nil
-}
-
 func URLJoin(endpoint string, paths ...string) string {
 	u, err := url.Parse(endpoint)
 	if err != nil {