Handle client errors of the "add" command
HandlerError must be a sub class of StandardError
Define status code by the error class
Assert raised exception correctly for an unknown table
Add a test of the "add" command for a request without "table"
Add a test of the "add" command for a request without "key"
Generate response body by the error class
Add a test for missing primary key
HandlerError should have only detail
Messenger should not receive error object
Handle HandlerError on the plugin layer
Fix typo
Output the name of the error without full class path
Don't output detail
Fix typo
Define base class for responsible errors with general name
ResponsibleError must be a sub class of StandardError
Add drntest cases for error of "add" command
Merge branch 'master' of 192.168.1.21:~piro/groonga/fluent-plugin-droonga into HEAD

Conflicts:
	lib/droonga/handler_messenger.rb
	lib/droonga/handler_plugin.rb
Add drntest cases for common errors