Firefox addon interface changed again, add variant needles

We can probably throw the other needles away once Firefox 52
makes it to all release's stable repos.

needles/firefox/addon_install-20170425.json

@@ -0,0 +1,22 @@
+{
+  "tags": [
+    "firefox_addon_install"
+  ],
+  "area": [
+    {
+      "width": 35,
+      "ypos": 142,
+      "type": "match",
+      "xpos": 60,
+      "height": 35
+    },
+    {
+      "height": 17,
+      "width": 44,
+      "type": "match",
+      "xpos": 386,
+      "ypos": 281
+    }
+  ],
+  "properties": []
+}

needles/firefox/addon_install-kde-20170425.json

@@ -0,0 +1,22 @@
+{
+    "area": [
+        {
+            "height": 33,
+            "type": "match",
+            "width": 34,
+            "xpos": 60,
+            "ypos": 107
+        },
+        {
+            "height": 17,
+            "type": "match",
+            "width": 44,
+            "xpos": 358,
+            "ypos": 226
+        }
+    ],
+    "properties": [],
+    "tags": [
+        "firefox_addon_install"
+    ]
+}

needles/firefox/addon_success-20170425.json

@@ -0,0 +1,22 @@
+{
+  "area": [
+    {
+      "height": 33,
+      "width": 33,
+      "xpos": 61,
+      "type": "match",
+      "ypos": 107
+    },
+    {
+      "width": 20,
+      "type": "match",
+      "xpos": 949,
+      "ypos": 70,
+      "height": 19
+    }
+  ],
+  "tags": [
+    "firefox_addon_success"
+  ],
+  "properties": []
+}