Build: Update grunt-compare-size to latest, add it's .sizecache.json to .gitignore

Author: jzaefferer

.gitignore

@@ -1,2 +1,3 @@
 dist
 node_modules
+.sizecache.json

package.json

@@ -63,7 +63,7 @@
 		"grunt-contrib-qunit": "0.2.0",
 		"grunt-contrib-csslint": "0.1.1",
 		"grunt-contrib-cssmin": "0.4.2",
-		"grunt-compare-size": "0.3.1",
+		"grunt-compare-size": "0.4.0-rc.3",
 		"grunt-html": "0.3.3",
 		"grunt-git-authors": "1.2.0",
 		"rimraf": "2.1.4",