issue#263 return from hive_app_next_iteration when waiting for 'live' HAF

Previously an apllication waited in app_next_iteration almost 'identifiely' for a moment when HAF reach 'LIVE' stage what makes impossible to break with SIGINT and holds long-standing transaction. Now when HAF is before 'LIVE' then app_next_iteration move app to 'wait_for_haf' stage and returns null block range after 500ms. Because no blocks range is returned application is forced to back ask again for blocks.