Admin view should handle more than 9 questions

fix regular expression to handle question index with more than
one digit
Correct election pdf report CreationDate value

reportlab memoizes timestamp used in CreationDate metadata key in the
module variable reportlab.pdfbase.pdfdoc._NOWT. This causes incorrect dates
to be set in documents which are generated from within a long lived
process (every document will share the timestamp cached for the first
document created from within the corresponding process).

In order to fix this we force _NOWT invalidation before each document
generation.