Adds some feature to the update script [specific BibLibre use]

First fill the trello api secret key and the trello api token (see
pod).

You can launch this script like:
  perl trello-update.pl -v
will show you difference between the trello and the bug statuses on
bugzilla.

Using the --confirm flag, the script will update the trello cards
(moving cards in the right list).

Finally, after exporting the google doc as a csv file, the script will
check that all rows has the good status.

Google doc (public access), tab "Devs":
https://docs.google.com/a/biblibre.com/spreadsheet/ccc?key=0AuZF5Y_c4pIxdHE3S0RXMjJqSzZ3d1BVUmxpRnRVUUE#gid=3

Trello board (public access):
https://trello.com/board/community-biblibre-koha-devs/4f1d247284210f0e6300d7d7

You have to have write access on the trello board for getting an api
token and are allow to move cards.