fixing undefined proptype warning and reversed disableddates to enableddates

[codGmer]

fixing Warning: Invalid argument supplied to oneOfType. Expected an array of check functions, but received undefined at index 0.

and reversed disableddates to enableddates, maybe create both parameters?

[peacechen]

Thanks @codGmer for the PR. I like the positive prop versions e.g. enabledDates. There are existing projects using disabledDates and we shouldn't break them. Please restore the disabled* props and add your enabled* props alongside them. That way users can choose which one to use.

Another PR fixed the propTypes on selectedDayStyle, so please revert the changes to ViewPropTypes.style.

[peacechen]

@codGmer
Will you address the points above? Your contributions would be valued, but it needs to remain in sync with the main repo.