[DC-2019] add Split Software as platinum sponsor
[DC-2019] add Split Software as platinum sponsor

Also remove vestigial sponsor stanza earlier in the data; that's not
where we're listing them.

Signed-off-by: Robb Kidd <a629c362624370ec351e141df0bd1d27621ff790@thekidds.org>

gomex/devopsdays-web,gomex/devopsdays-web,gomex/devopsdays-web,gomex/devopsdays-web