Acq: Be fuzzy about case when retrieving EDI documents

The edi_fetcher relies on a routine in OpenILS::Acq::EDI to, among
other things, try to avoid fetching the same EDI document multiple times
when many rows in acq.edi_account refer to the same host and login
credentials.

Since in practice most vendors seem to run FTP servers for EDI on
Windows, not UNIX, and pathnames are therefore case-insensitive, that
test for other occurrences ought also to be case-insensitive.

If I were to look at this as a purist, I could argue that vendor servers
might sometimes by run on UNIX, and that for some reason it is possible
that different vendor-to-buyer EDI documents (order responses or
invoices) could have pathnames that differ only in the case of some
characters.  But that seems wildly unlikely.  If anyone does take this
possibility seriously, perhaps acq.edi_account needs a Boolean column to
indicate the remote host's case [in]sensitivity.

Signed-off-by: Lebbeous Fogle-Weekley <lebbeous@esilibrary.com>
Signed-off-by: Ben Shum <bshum@biblio.org>