support [test] and [live] groups in ~/.stripecli config file
add Stripe.api_version to requests
significantly DRY-up codebase. add `version` & `env` global-options. add several more command classes and expand existing ones.
New Commands include BalanceTransactions, Invoices, and Coupons
swap error-prone :method_missing for Stripe::CLI::Command.special to handle none-crud sub-commands in a uniform manner
update readme
update readme to include example output image
add api coverage for token objects, improve readme, improve interactive menu for coupon creation, some bug fixes
add recipient command suite, update balance_transactions list options, add upcoming invoice. update readme and bump version