Integrate button classes to CK-Editor
At the moment we can integrate all bootstrap button classes
Classnames:
btn btn-primary
btn btn-secondary
btn btn-success
btn btn-info
btn btn-warning
btn btn-danger
btn btn-link
btn btn-outline-primary
btn btn-outline-secondary
btn btn-outline-success
btn btn-outline-info
btn btn-outline-warning
btn btn-outline-danger