Introduces changes to the interface for custom Javascript components. This now allows JS modules to export a mount(element, component, props) function which can be used to bind new elements to the DOM instead of using the application's own React instance and specifying React as a peer dependency. This avoids a wide variety of potential issues with implementing custom components and opens up the possiblity for a wider variety of component implementations.

• modules with mount func should not have children - 94d006c
• limit to flask<2.0 - e7c11d0
• federate modules with mount function - bf63a62