https://github.com/daid/Cura/issues/37 package.sh does not run correctly when current directory is not script directory

package.sh

@@ -40,6 +40,11 @@ function checkTool
 # Actual build script
 #############################
 
+# Change working directory to the directory the script is in
+# http://stackoverflow.com/a/246128
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+cd $SCRIPT_DIR
+
 checkTool git "git: http://git-scm.com/"
 checkTool curl "curl: http://curl.haxx.se/"
 if [ $BUILD_TARGET = "win32" ]; then