Issue description

• components: ModalHeader
• reactstrap version #5.0.0-alpha.3
• import method umd/csj/es (if umd, are you using the "full" version (only for v5+)?)
• react version #16.0.0
• bootstrap version #4.0.0-beta

What is happening?

I've included ModalHeader component in next way:

<ModalHeader cssModule={bs} toggle={this.toggle}>Header</ModalHeader>

1. cssModules prop was passed
2. toggle prop was passed

In this case close button still have class close but it should take it from css module.