Fixed SelectField activeLabel bug (version 2)
Fixed SelectField activeLabel bug (version 2)

Moved the activeLabel updates when the value or the
menuItems prop changes to the componentWillUpdate. Without this update,
the activeLabel will be reset before the new activeLabel could be set.

Should hopefully close #300 again.

mlaursen/react-md,lwhitlock/grow-tracker,mlaursen/react-md,mlaursen/react-md