Added default language pack (en-gb)

admin/user/user_group.php

@@ -0,0 +1,23 @@
+<?php
+// Heading
+$_['heading_title']    = 'User Groups';
+
+// Text
+$_['text_success']     = 'Success: You have modified user groups!';
+$_['text_list']        = 'User Group';
+$_['text_add']         = 'Add User Group';
+$_['text_edit']        = 'Edit User Group';
+
+// Column
+$_['column_name']      = 'User Group Name';
+$_['column_action']    = 'Action';
+
+// Entry
+$_['entry_name']       = 'User Group Name';
+$_['entry_access']     = 'Access Permission';
+$_['entry_modify']     = 'Modify Permission';
+
+// Error
+$_['error_permission'] = 'Warning: You do not have permission to modify user groups!';
+$_['error_name']       = 'User Group Name must be between 3 and 64 characters!';
+$_['error_user']       = 'Warning: This user group cannot be deleted as it is currently assigned to %s users!';