Use the same create database option as Rails Rakefile
Use the same create database option as Rails Rakefile

* DEFAULT CHARACTER SET utf8mb4 for MySQL

https://github.com/rails/rails/blob/5431e17733366da1fd10f2cd3039d66a56012683/activerecord/Rakefile#L97-L98

```
%x( mysql --user=#{config["arunit"]["username"]} --password=#{config["arunit"]["password"]} -e "create DATABASE #{config["arunit"]["database"]} DEFAULT CHARACTER SET utf8mb4" )
%x( mysql --user=#{config["arunit2"]["username"]} --password=#{config["arunit2"]["password"]} -e "create DATABASE #{config["arunit2"]["database"]} DEFAULT CHARACTER SET utf8mb4" )
```

* Do not specify `DEFAULT COLLATE` as Rails Raketask removed

https://github.com/rails/rails/commit/d54d0c95750e2693da495b75ac5fa0280253972d#diff-6c25b8e13c63a297ab5298948548caef

> There should be no "one size fits all" collation in MySQL 5.7.
> Let MySQL server choose the default collation for Active Record
> unit test databases.

* Use `-E UTF8 -T template0` option for PostgreSQL database

https://github.com/rails/rails/blob/5431e17733366da1fd10f2cd3039d66a56012683/activerecord/Rakefile#L116-L117

```
%x( createdb -E UTF8 -T template0 #{config["arunit"]["database"]} )
%x( createdb -E UTF8 -T template0 #{config["arunit2"]["database"]} )
```

rails/rails-dev-box,yahonda/rails-dev-box