Release addon 0.12.0

Author: marco-c

addon/manifest.json

@@ -2,7 +2,7 @@
   "author": "Marco Castelluccio",
   "manifest_version": 2,
   "name": "Gecko Code Coverage",
-  "version": "0.11.0",
+  "version": "0.12.0",
   "icons": {
     "270": "assets/coverage.jpg"
   },