fix(ButtonGroup): allow value 0 (Number) as valid value for a bs-button (#105).
fix(ButtonGroup): allow value 0 (Number) as valid value for a bs-button (#105).

Thanks to @arohr
kaliber5/ember-bootstrap,srvance/ember-bootstrap,jelhan/ember-bootstrap,srvance/ember-bootstrap,kaliber5/ember-bootstrap,jelhan/ember-bootstrap