Fix Sequel::DatabaseConnectionError on db:create:all task

[olivierlacan]

Prior to this commit, running bin/rails db:create:all in a new Rails app with sequel-rails configured to replace ActiveRecord resulted in this error:

Sequel::DatabaseConnectionError: PG::ConnectionBad: FATAL: database "rails_app_development" does not exist

It then failed to create either the development or test databases.

This commit includes db:create:all in the commands checked to enable skip_connect and avoid attempting to connect to the database before it's been created.

Previously only db:create was checked. I don't want to make the check too permissive so I'm specifying the full command and still checking the ARGV array of command line arguments.

This extends the fix I originally submitted with #148.

[olivierlacan]

@JonathanTron Actually I'd avoid releasing 1.0.1 until this is reviewed and merged.

[JonathanTron]

@olivierlacan Thanks !