Bug 12750: koha-create should be able to configure the Z39.50/SRU server

This patch adds two parameters to the koha-create command:

 --enable-sru: makes the koha-create script enabled the SRU server for
               the created instance

 --sru-port:   lets the user specify a desired port for the SRU server
               to listen at. It defaults to 7090

To test:
- Apply the patch on top of master
- Build your own package and install / can be tested just using the koha-create
  command on a 3.16+ packages install
- Create an instance as usual (i.e. without --enable-sru and --sru-port)
=> SUCCESS: The instance is created, the publicserver sections are
            both commented out. The first publicserver section has 7090 set as the
            listening port.
- Create an instance as usual, passing --sru-port 456
=> SUCCESS: The instance is created, the port is set but the publicserver sections
            are commented out
- Create an instance with --enable-sru (with and without --sru-port)
=> SUCCESS: Verify the instance is created as expected, with the SRU server enabled
            (port 7090 if no --sru-port passed, the one we chose otherwise).
- Verify that the docs also talk about this new parameters addition.
- Sign off :-D

Regards
To+

Sponsored-by: Universidad Nacional de Cordoba
Signed-off-by: Jesse Maseto <jesse@bywatersolutions.com>

Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>
Signed-off-by: Robin Sheat <robin@catalyst.net.nz>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>