port GildedRose Java/Ruby to R language, add a RUnit test stub

R/runit_gilded_rose.R

@@ -0,0 +1,7 @@
+source('gilded_rose.R')
+
+test.foo <- function() {
+  items <- list( item('foo', 0, 0) )
+  items <- update_quality(items)
+  checkEquals('fixme', items[[1]]$name);
+}