* add a "config" table to the database, and set the site_type value to "development" by default
* if site_type is production, get_all_button_names() should not return buttons with unimplemented skills
* UI should only print the warning about choosing unimplemented buttons if there are any
* typo
* add comments about site_type
Merge pull request #640 from cgolubi1/600_config_table

add config table to database and populate it