merged_configure_proxy overwrites name of proxy

[okkez]

The name of proxy object which is returned by Fluent::Configurable#merged_configure_proxy is Fluent::Plugin::Base. I expected real plugin name such as Fluent::Plugin::DummyInput.
This is not useful for debug.

https://github.com/fluent/fluentd/blob/master/lib/fluent/configurable.rb#L159..L167

configurables = ancestors.reverse.select{ |a| a.respond_to?(:configure_proxy) } # => [Fluent::PluginBase, ..., Fluent::Plugin::DummyInput]
configurables.map{ |a| a.configure_proxy(a.name || a.object_id.to_s) }.reduce(:merge)

In Fluentd v0.14.0:

merged_configure_proxy.name # => "Fluent::Plugin::Base"

I expected:

# For example, when we use in_dummy plugin
merged_configure_proxy.name # => "Fluent::Plugin::DummyInput"