mc: run FTB installer from correct location

We have pushd'ed into the directory so do not prefix the shell script
with the directory name.

minecraft-server/start-deployFTB

@@ -87,11 +87,11 @@ fi
 
 if [ -e ${FTB_DIR}/FTBInstall.sh ]; then
   pushd ${FTB_DIR}
-  sh ${FTB_DIR}/FTBInstall.sh
+  sh FTBInstall.sh
   popd
 elif [ -e ${FTB_DIR}/Install.sh ]; then
   pushd ${FTB_DIR}
-  sh ${FTB_DIR}/Install.sh
+  sh Install.sh
   popd
 fi