Revert "[refrepo] Add information about 401 error"

This reverts commit f79352ca.

lib/refrepo/utils.rb

@@ -15,7 +15,7 @@ module RefRepo::Utils
       o = {}
       puts "Check the documentation https://www.grid5000.fr/w/TechTeam:Reference_Repository#Credentials and your ~/.grid5000_api.yml file"
     end
-    d = URI.open("#{conf['uri']}/#{conf['version']}/#{path}", o).read
+    d = open("#{conf['uri']}/#{conf['version']}/#{path}", o).read
     return JSON::parse(d)
   end