Allow HTMLFormElement attributes to be passed to a Formsy form

[twisty]

Allow HTMLFormElement attributes to be passed to a Formsy form

This fixes a use case where I wanted to set a class attribute on the <form /> output by Formsy.

This works fine at runtime (it is passed through in nonFormsyProps), however passing a className prop is not allowed in the FormsyProps definition.

This PR expands the FormsyProps definition to explicitly allow passing HTMLFormElement attributes that are passed through (nonFormsyProps) to the <form />.

[twisty]

@rkuykendall Should I build and commit /dist, too?

[rkuykendall]

@twisty Nope! 😄Jest now runs off the source, and the project is automatically built and committed on npm deploy!