update gems version.

Note for sequel gem. it does not work with 3.48.0 or later versions.
so we use 3.47.0. need to fix after_initialize() hook and the model
classes using single table inheritance plugin.
use https in Gemfiles.
use modified eventmachine from github.com/axsh/eventmachine.git.
upgrade ruby binary to p448.
git pull if ruby-build.git is available locally.