make some css class names more generic

src/views/validation-view.jsx

@@ -78,10 +78,10 @@ class ValidationView extends React.PureComponent {
         }</FormattedMessage>
         </div>
         <div className="dialog-buttons">
-          <button className="blue" onClick={this.handleSubmit}>
+          <button className="primary" onClick={this.handleSubmit}>
             <FormattedMessage id="button_confirm" defaultMessage="Confirm" description="Button [Confirm]" />
           </button>
-          <button className="white" onClick={this.handleCancel}>
+          <button className="secondary" onClick={this.handleCancel}>
             <FormattedMessage id="button_cancel" defaultMessage="Cancel" description="Button [Cancel]" />
           </button>
         </div>