remove gem dependencies: make fog-aws optional, and no longer vendor acme-client gem.

leap_cli.gemspec

vendor/acme-client/Gemfile

vendor/acme-client/LICENSE.txt

vendor/acme-client/README.md

vendor/acme-client/acme-client.gemspec

vendor/acme-client/lib/acme-client.rb

vendor/acme-client/lib/acme/client.rb

vendor/acme-client/lib/acme/client/certificate.rb

vendor/acme-client/lib/acme/client/certificate_request.rb

vendor/acme-client/lib/acme/client/crypto.rb

vendor/acme-client/lib/acme/client/error.rb

vendor/acme-client/lib/acme/client/faraday_middleware.rb

vendor/acme-client/lib/acme/client/resources.rb

...or/acme-client/lib/acme/client/resources/authorization.rb

vendor/acme-client/lib/acme/client/resources/challenges.rb

.../acme-client/lib/acme/client/resources/challenges/base.rb

...acme-client/lib/acme/client/resources/challenges/dns01.rb

...cme-client/lib/acme/client/resources/challenges/http01.rb

...-client/lib/acme/client/resources/challenges/tls_sni01.rb

vendor/acme-client/lib/acme/client/resources/registration.rb