* Increase DNS timeout from 1 second to 5 seconds for MX check

1 seconds is rather short when using a recursive DNS resolver which
hasn't got a cached result already available. Use 5 seconds instead,
which is the timeout value we use for outgoing HTTP queries.

* Add more precise error messages for invalid e-mail addresses

* Add tootctl email_domains (block|unblock)

* fix codeclimate issues.

* fix codeclimate issues.

* fix codeclimate issues.

* add list subcommand, remove log_action.

* fix codeclimate issues.

* filter duplicate hostnames,ips before block

* rebase from currnet master branch.
rename email_domains_cli.rb to email_domain_blocks_cli.rb .
rename Mastodon::EmailDomainsCLI to Mastodon::EmailDomainBlocksCLI .
rename command email_domains to email-domain-blocks . (Thor recognizes both of - and _ )
rename subcommand block to add .
rename subcommand unblock to remove .
change the color in list subcommand to while for domain or cyan for childlen.
don't use include() in list subcommand.
suppress console output about succeeded entry.
add console output about count of processed/skipped.
remove capitalization in subcommand description.
remove long_desc in subcommand 'remove'.
remove duplicate where in subcommand 'remove'.

* fix codeclimate issue.