(appbase) Add option to print default configuration template
(appbase) Add option to print default configuration template

Add an option to print the default configuration template. This could be useful to packagers (to create an /etc/ template without making /etc writable) or for users to see a diff of their config.ini compared to future defaults.

EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos,EOSIO/eos