[Ubuntu] upgrade to qgis2.18

Tue Feb 27 11:16:17 PST 2018

Hi,

recently QGIS 3.0 has been published. So QGIS 2.18 became current LTR.
It's time to upgrade QGIS 2.14 to 2.18 ASAIU. Today I uploaded new
package (2.18.17) to ubuntugis experimental for xenial. If no
objection I will copy new packages to UbuntuGIS Unstable in the next
days.

Martin

-- 
Martin Landa
http://geo.fsv.cvut.cz/gwiki/Landa
http://gismentors.cz/mentors/landa