\imap_header dosen't work with UID

http://us1.php.net/manual/en/function.imap-header.php
http://us1.php.net/manual/en/function.imap-headerinfo.php

 msg_number
    The message number

http://us1.php.net/manual/en/function.imap-msgno.php
imap_msgno — Gets the message sequence number for the given UID

I don't know why PHP dosen't has a way to read the header with the UID but this is the solution.
Merge branch 'ysramirez-patch-1'
Add test for search