Save page numbers and pick them up again

Two step validation checks, like checking with the server for uniqueness
of a textbox value, were losing the requested new page number on
mulitpage forms.  This code saves the requested page number if the
initial validation fails, and picks it up again if the second validation
is successful.
Checking if savedPage is defined fixes submit bug
Fix typo
Fix typo 2
Merge pull request #94 from jegelstaff/Check-unique-on-multipage-forms

Save page numbers and pick them up again