v4.0.0

Full Changelog

Fixed bugs:

• Fix for 3D-Secure payments on cart page checkout #49 (spaghetticode)

Closed issues:

• Custom stripe element field options (e.g for showing a credit card icon) #41
• Clearer documentation on how to implement #15

Merged pull requests:

• Relax solidus_support dependency #48 (kennyadsl)