Extra Stat collection (#407)

* Cleaned up error interceptor to avoid sending auth errors (when a 500 occurs) to sentry as auth errors aren't issues.

* Added extra stat collection

* Fixed a bad gitignore which ignored anything in a stats directory

API/DTOs/Stats/UsageStatisticsDto.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace API.DTOs.Stats
+{
+    public class UsageStatisticsDto
+    {
+        public UsageStatisticsDto()
+        {
+            MarkAsUpdatedNow();
+            ClientsInfo = new List<ClientInfoDto>();
+        }
+
+        public string InstallId { get; set; }
+        public DateTime LastUpdate { get; set; }
+        public UsageInfoDto UsageInfo { get; set; }
+        public ServerInfoDto ServerInfo { get; set; }
+        public List<ClientInfoDto> ClientsInfo { get; set; }
+
+        public void MarkAsUpdatedNow()
+        {
+            LastUpdate = DateTime.UtcNow;
+        }
+
+        public void AddClientInfo(ClientInfoDto clientInfoDto)
+        {
+            if (ClientsInfo.Any(x => x.IsTheSameDevice(clientInfoDto))) return;
+
+            ClientsInfo.Add(clientInfoDto);
+        }
+    }
+}