plugin ruby:use grn_plugin_command_create API instead of the macro
suggest:use grn_plugin_command_create API instead of the macro
table:use grn_plugin_command_create API instead of the macro
Merge pull request #177 from naoa/use-command-create-api-instead-of-macro

Builtin plugins use grn_plugin_command_create API  instead of macro

Patch by Naoya Murakami. Thanks!!!