Fix for failing tests (MockViewState no instance of ViewState)

MockViewState instances have not been recognized as ViewState instances because
valueview.ViewState.js got loaded twice. After the first time, jQuery.valueview.ViewState
is defined and jQuery.valueview.MockViewState inherits from it. At a later point the
valueview.ViewState.js gets loaded again and the ViewState constructor from the first
time is being overwritten while the prototype chain of MockViewState is still holding
a reference to the first ViewState constructor while jQuery.valueview.ViewState now is
a reference to the second ViewState constructor.
This also fixes some other related minor issues, e.g. the "constructor" property not being
properly set and some missing dependency.

Change-Id: I4cee640185132d659308a3135ca201ae64a23a16