cli: fix cli of policy
cli: fix cli of policy

 - fix bug that del all command can not be used
 - fix bug that can enter the option of conditions other than add subcommand
 - fix bug that can not enter the option of actions in the routepolicy (add) subcommand
 - chenge syntax of routepolicy (add) subcommand
   aggregate the option flags of conditions and actions
   + before
     % gobgp routepolicy add <policy> <statement name> conditions [<option flags of conditions> ...]
     % gobgp routepolicy add <policy> <statement name> actions [<option flags of actions> ...]
   + after
     % gobgp routepolicy add <policy> <statement name> [<option flags of conditions and actions>...]

a16/gobgp,ramrunner/gobgp,Dipsingh/gobgp,a16/gobgp,tamihiro/gobgp,YujiOshima/gobgp,ishidawataru/gobgp,j-kato/gobgp,a16/gobgp,h-naoto/gobgp,ramrunner/gobgp,fujita/gobgp,osrg/gobgp,ramrunner/gobgp,YujiOshima/gobgp,ishidawataru/gobgp,fujita/gobgp,j-kato/gobgp,j-kato/gobgp,YujiOshima/gobgp,fujita/gobgp,h-naoto/gobgp,tamihiro/gobgp,Dipsingh/gobgp,postfix/gobgp,a16/gobgp,tamihiro/gobgp,a16/gobgp,postfix/gobgp,h-naoto/gobgp,osrg/gobgp,tamihiro/gobgp,a16/gobgp,postfix/gobgp,osrg/gobgp,Dipsingh/gobgp,a16/gobgp,ishidawataru/gobgp,osrg/gobgp,fujita/gobgp