React-datetime version 3.0.4 not control value setState with null, undefined and invalid date

### I'm Submitting a ...

```
[x] Bug report
[ ] Feature request
[ ] Support request
```

### Steps to Reproduce
1. Fill in/initialize the value in the field from a state
2. Replace the value in the state with null/undefined/invalid date

### Expected Results
The value has changed

### Actual Results
The value has not changed

### Minimal Reproduction of the Problem
Reproducible example: https://codesandbox.io/s/objective-neumann-ctgb0?file=/src/App.js

### Other Information (e.g. stacktraces, related issues, suggestions how to fix)
Version 2.16.3 of react-datetime doesn't have this problem.

Start with the linked CodeSandbox reproduction and confirm the behavior using react-datetime 3.0.4 with state values set to null, undefined, and an invalid date. Compare the result with version 2.16.3 and trace the component's controlled-value handling. Done means the displayed value changes when the state is replaced with each reported value.

Written by the indexing model from the issue text.