showError API update, fix to event.persist on blur

showError can now accept function as second argument which returns hint (jsx).

validateAll behavior update

1. validateAll now returns errors map.
2. Specified propTypes.

Release 2* stable

Finally we've some tests, up-to-date dependencies and README. Library has been massively refactored and even completely rewritten few times.

There is a lot of work anyway:

1. Prepare few example usages with other modules (such material-ui).
2. Add more tests.
3. More refactoring.