Bug 15427 : Enable TLS support for MySQL

Bug 15427 : Enable TLS support for MySQL

In summary, changes are:
1) If you have chosen MySQL, Makefile.PL will ask you if you want TLS (default:
"no"), and then the locations for CA cert, client cert and client key
(reasonable defaults are provided). Settings <tls>, <ca>, <cert> and <key> are
added in koha-conf.xml
2) If <tls>yes</tls> in koha-conf.xml, the installer and database connection
scripts add the TLS options in both DBI connection strings and mysql command
line

To test
1/ Apply patch
2/ Check everything still works and db connections are the same as before
3/ Either run Makefile.PL and step through the options or edit your koha-conf.xml to
enable TLS
4/ Check db connections are still working

Patch provided to me by Dimitris Kamenopoulos and I reformatted it into a git patch,
any errors are probably mine

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>