fix incomplete lang patching, add en-gb stub

en-gb is empty, so it's patched with en-us strings. Added so DD/MM/YY
date formatting was possible in the ui.

lang/admin/en-gb.json

@@ -0,0 +1,5 @@
+{
+    "meta": {
+        "name": "English (GB)"
+    }
+}

lang/common/en-gb.json

@@ -0,0 +1,5 @@
+{
+    "meta": {
+        "name": "English (GB)"
+    }
+}

lang/email/en-gb.json

@@ -0,0 +1,5 @@
+{
+    "meta": {
+        "name": "English (GB)"
+    }
+}

lang/form/en-gb.json

@@ -0,0 +1,5 @@
+{
+    "meta": {
+        "name": "English (GB)"
+    }
+}

lang/setup/en-gb.json

@@ -0,0 +1,5 @@
+{
+    "meta": {
+        "name": "English (GB)"
+    }
+}