ExpertSenderTest: tests are marked as skipped when no configuration is provided
Merge pull request #5 from MonsterMediaGroup/skipTestsWhenNoConfig

ExpertSenderTest: tests are marked as skipped when no configuration is provided
ExpertSenderEnum: added ::getTypes(), ::getOperators(), ::getOrders(), ::getModes() methods
Added Request\AddUserToList class – provides a clear interface to create user-list subscriptions (plus tests)
ExpertSenderTest: getParam() helper method + example configuration in params.json.dist