dotfile is parsed twice when executing `udpate` command

[yujideveloper]

dotfile is parsed twice when executing udpate command on v4.0.0.

1. First time, it is parsed to get ssh config path
   • https://github.com/mirakui/ec2ssh/blob/v4.0.0/lib/ec2ssh/command/update.rb#L15
   • https://github.com/mirakui/ec2ssh/blob/v4.0.0/lib/ec2ssh/command.rb#L12-L18
2. Second time, it is parsed to build host lines
   • https://github.com/mirakui/ec2ssh/blob/v4.0.0/lib/ec2ssh/command/update.rb#L25-L31