Rename .tgz as .tar.gz (BMK-110)

Closes BMK-110

.gitlab-ci.sh

@@ -100,7 +100,7 @@ if [ "$stage" == "build" ]; then
 
   #Create tarball of JOBDIR results
   echo "creating tarball of json and log results for artifacts"
-  find $JOB_DIR/results -name "*.json" -or -name "*.log" | tar -cvzf $CI_PROJECT_DIR/results.tgz -T -  
+  find $JOB_DIR/results -name "*.json" -or -name "*.log" | tar -cvzf $CI_PROJECT_DIR/results.tar.gz -T -  
 
   # Clean up: remove directory CVMFS_VOLUME
   # Also unmount cvmfs and delete mount points below CVMFS_VOLUME if necessary (but main.sh