Added fahrenheit to .weather command

NadekoBot.Core/Services/StandardConversions.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace NadekoBot.Core.Services
+{
+    public class StandardConversions
+    {
+        public static double CelsiusToFahrenheit(double cel)
+        {
+            return cel * 1.8f + 32;
+        }
+    }
+}