PauseManager moved to Shared (#3288)

* Namespace changes for moving IPauseManager to shared.

* Namespace changes for moving ITimerManager from Timers to Timing.

* Rebase Fixes.

* Update engine submodule to v0.3.8

Content.IntegrationTests/ContentIntegrationTest.cs

@@ -7,11 +7,11 @@ using Content.Server.Interfaces.GameTicking;
 using Content.Shared;
 using NUnit.Framework;
 using Robust.Server.Maps;
-using Robust.Server.Timing;
 using Robust.Shared.ContentPack;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
 using Robust.Shared.Network;
+using Robust.Shared.Timing;
 using Robust.UnitTesting;
 
 namespace Content.IntegrationTests