Update a couple of Firefox needles

In latest Branched, 'Close Tabs' button has an upper-case T, and
the addon install button is a darker blue.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

needles/firefox/addon_install-20190319.json

@@ -0,0 +1,22 @@
+{
+  "area": [
+    {
+      "ypos": 108,
+      "type": "match",
+      "width": 35,
+      "height": 35,
+      "xpos": 234
+    },
+    {
+      "type": "match",
+      "ypos": 272,
+      "width": 26,
+      "height": 14,
+      "xpos": 536
+    }
+  ],
+  "properties": [],
+  "tags": [
+    "firefox_addon_install"
+  ]
+}

needles/firefox/firefox_close_tabs-20190319.json

@@ -0,0 +1,15 @@
+{
+  "area": [
+    {
+      "height": 13,
+      "xpos": 668,
+      "ypos": 419,
+      "type": "match",
+      "width": 68
+    }
+  ],
+  "properties": [],
+  "tags": [
+    "firefox_close_tabs"
+  ]
+}