Remove needless "self"
Merge pull request #1 from yoshihara/remove-needless-self

Remove needless "self"
Use more proper name

file ->
yaml
Merge pull request #2 from yoshihara/use-more-proper-name

Use more proper name
Use proper name to match objects

yaml -> config_items

An object loaded by #load_file isn't YAML yet. I'm sorry to modify it
twice...
Merge remote branch 'yoshihara/use-proper-name-to-match-objects'
Use #join for generate String joind value with ","
Merge remote branch 'yoshihara/use-join-method-for-join-values'
Remove a needless variable.
Use $stderr instead of STDERR

$stderr is more proper because STDERR is the default standard error,
on the other hand, $stderr is one used by present process.
Fix indent.