iss-48 disconnect from Ruffnote

Authentication Table から Ruffnote 情報を削除
iss-48 disconnect from Ruffnote

PR指摘反映
・UsersControllerのdisconnectで、getかどうかの判定は不要なので削除
Merge pull request #62 from koala777/iss-48

iss-48 disconnect from Ruffnote (再)