URL-Encode reasons on Kick/Ban (#787)

This resolves #784

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -803,7 +803,7 @@ namespace Discord.API
             options = RequestOptions.CreateOrClone(options);
 
             var ids = new BucketIds(guildId: guildId);
-            string reason = string.IsNullOrWhiteSpace(args.Reason) ? "" : $"&reason={args.Reason}";
+            string reason = string.IsNullOrWhiteSpace(args.Reason) ? "" : $"&reason={Uri.EscapeDataString(args.Reason)}";
             await SendAsync("PUT", () => $"guilds/{guildId}/bans/{userId}?delete-message-days={args.DeleteMessageDays}{reason}", ids, options: options).ConfigureAwait(false);
         }
         public async Task RemoveGuildBanAsync(ulong guildId, ulong userId, RequestOptions options = null)
@@ -988,7 +988,7 @@ namespace Discord.API
             options = RequestOptions.CreateOrClone(options);
 
             var ids = new BucketIds(guildId: guildId);
-            reason = string.IsNullOrWhiteSpace(reason) ? "" : $"?reason={reason}";
+            reason = string.IsNullOrWhiteSpace(reason) ? "" : $"?reason={Uri.EscapeDataString(reason)}";
             await SendAsync("DELETE", () => $"guilds/{guildId}/members/{userId}{reason}", ids, options: options).ConfigureAwait(false);
         }
         public async Task ModifyGuildMemberAsync(ulong guildId, ulong userId, Rest.ModifyGuildMemberParams args, RequestOptions options = null)