bower.json: Correct amber version required.

prod is amd using amber/boot, which was introduced in 0.12.6.
#imports: is used, which was working from 0.14.4.

bower.json

@@ -24,10 +24,11 @@
     "tests"
   ],
   "dependencies": {
-    "amber": "*",
+    "amber": ">=0.12.6",
     "amber-contrib-jquery": ">=0.1.0"
   },
   "devDependencies": {
+    "amber": ">=0.14.4",
     "amber-ide-starter-dialog": "^0.1.0",
     "amber-contrib-legacy": "^0.2.0",
     "helios": ">=0.4.3"