Define Maven plugin repository for gs-maven-wagon artifact
Define Maven plugin repository for gs-maven-wagon artifact

Without having the plugin repository specified Maven is unable to find
and download the gs-maven-wagon artifact and the build fails.

Change-Id: If726f0bdcfa94449cd1427c78d2c734e175ce99b
Signed-off-by: Edwin Kempin <b444e279ad95fdef4fbdd82c813b624595df204a@sap.com>

thinkernel/gwtorm,thinkernel/gwtorm,GerritCodeReview/gwtorm,GerritCodeReview/gwtorm