SmartForm minor bug fixes Jan 2020

[ErikDakoda]

• Fixed bug: SmartForm.initField() set each field's document property to the initial document, instead of the current document, resulting in bugs like Nested Schema document update not working
• Fixed bug: FormComponent.getDerivedStateFromProps() would fail when intlOrRegularValue was null (because typeof null === 'object'); it's possible that this should not normally occur, but it has occurred in my codebase because of Invariant Violation errors thrown by Apollo, likely because we have not upgraded to Apollo Client 3 cache
• Fixed bug: Material UI Number input would not behave correctly when the user entered "0." quickly (the period would disappear)
• Fixed bug: Creating a new document with SmartForm would fail when no Apollo errors occurred (meta prop was missing)
• Fixed bug: getString() in intl.js would fail if the defaultMessage passed was not a string

[ErikDakoda]

I would like someone (@eric-burel) to quickly review this, primarily because I am changing SmartForm.initField() to change field.document from the initial document to the current document. I believe this is a bug, but it's possible that some users of the code are expecting field.document to contain the initial document.