Allow passing props to material-ui's InputLabel

[Floriferous]

We're using the material-ui variant of uniforms, and we've had the issue where we want to use displayEmpty of the Select, which conflicts with the InputLabel, as can be seen in this issue: mui/material-ui#12336

The shrink prop on InputLabel would fix it, but there's currently no way to customize it, as all SelectField props are spread on the Select component only.

Not sure what's best, picking all props that should be on InputLabel (shrink required disableAnimation for example), or spread a new prop labelProps ?

[radekmie]

Hi @Floriferous. Sounds good, as long as each InputLabel will be handled, not only the SelectField one. In this case, labelProps would be better, as there might be conflicts in prop names. Would you like to submit a PR for that?

[radekmie]

Closed in #485.