Bug 36818: Escape characters in file names uploaded

Bug 36818: Escape characters in file names uploaded

To test:
1/ create a file named something like 'execute`curl blog.bigballofwax.co.nz`.zip'
   Where the domain is one you can watch the logs from
2/ Upload this file as a cover image
3/ Check /var/lib/koha/sitename/tmp/koha_sitename/ and see unescaped filenames
4/ Choose process, check the logs of the webserver see the connection has been made
5/ Apply the patch
5/ Repeat 2 & 3 and see the filename is now escaped
6/ Choose process and check no errors but no no remote execution occurs
7/ Test uploading actual zip file and images still works

Signed-off-by: Amit Gupta <amit.gupta@informaticsglobal.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Wainui Witika-Park <wainuiwitikapark@catalyst.net.nz>