Switch from commandline zip/unzip to PHP ZipArchive class

[Aaron Wells]

We get a steady stream of support requests from people on shared hosting or Windows, who can't find their command-line zip & unzip utilities.

There's really no reason for us to be using those anymore, though. PHP 5.3 ships with a fully functional zip library, and we should use that instead: http://nz1.php.net/manual/en/book.zip.php

[Aaron Wells (u-aaronw)]

Patch for master: https://reviews.mahara.org/#/c/4762/

[Mahara Bot (dev-mahara)]

Reviewed: https://reviews.mahara.org/4762
Committed: https://git.nzoss.org.nz/mahara/mahara/commit/46d61c4ecdf6fe531b66fb1185e4ca146d7cb2a1
Submitter: Robert Lyon (<email address hidden>)
Branch: master

commit 46d61c4ecdf6fe531b66fb1185e4ca146d7cb2a1
Author: Jono Mingard <email address hidden>
Date: Fri May 15 14:46:21 2015 +1200

Use ZipArchive for export and import (Bug #1338381)

Removes the dependency on commandline zip/unzip utilities in
favour of PHP's ZipArchive class

Change-Id: Id7f0833edd36529ac778feb9cbe97d4eb70f403c