Makefile in string_tools-0.4.0 vs Makefile in string_tools-0.5.0

@@ -15,5 +15,9 @@
 	fi
 	${BUNDLE} install ${BUNDLE_OPTIONS}
 
 appraisal/install:
 	${BUNDLE} exec ${APPRAISAL} install
+
+clear:
+	rm -rf gemfiles
+	rm -f Gemfile.lock