translations Makefile recreates the translations even if this not important

[Fadiabb]

Everytime translations is called triggers a new creation of .po files and thus a new translations.json file whithout checking if there are any updates in this files and if its necessary to create new ones.
this behavoir is inefficient since we initialze new files with the same content.

[Fadiabb]

Solution

• Change target translations to only be remade if one of
  the *.po files changes.Technically is only directly depends
  on these files

The following diff should improve this behavior:

--- a/Makefile
+++ b/Makefile
@@ -49,6 +49,6 @@ translations: ./$(OUTPUT_DIR)/translations.json
              fi; \
      done;

-$(OUTPUT_DIR)/translations.json: clean /tmp/template.pot
+$(OUTPUT_DIR)/translations.json: $(LOCALE_FILES)
      mkdir -p $(OUTPUT_DIR)
      gettext-compile --output $@ $(LOCALE_FILES)