add a new property to kipi plugin desktop file to register libkipi so version...

add a new property to kipi plugin desktop file to register libkipi so version used to compile kipi-plugins
Plugin Loader check now this property to see if plugin is loadable in memory or not. This prevent crash with old plugins compiled with libkipi 1.x
installed at the same time than plugins compiled with libkipi 2.x