Bug 9865: make SIP msg encoding configurable via SIPconfig.xml

Bug 9865: make SIP msg encoding configurable via SIPconfig.xml

The accounts->login tag in SIPconfig.xml can now accept a new
parameter, "encoding". It will be mostly used to encode to utf8.

For this, simply add the parameter: encoding="utf8"

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Works as advertised, does nothing if encoding is not set.
Blows up all the machines that can't handled utf8 if it is set :) But
that's not Koha's fault. :)

Patch rebased by Christophe Croullebois  <christophe.croullebois@biblibre.com>

Signed-off-by: Petter Goksoyr Asen <boutrosboutrosboutros@gmail.com>
But now I did it the right way! And I can confirm that this patch solves
all issues with mangled characters in SIP messages. Confirmed that it
looks good with Norwegian characters in patron name and in book titles.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 4a72f6b2375895c690dcaaaff26b07de53cfd518)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>