Gravity fixes (#4231)

git was being dumb so I just made a diff pr

Content.IntegrationTests/Tests/Gravity/WeightlessStatusTests.cs

@@ -4,6 +4,7 @@ using Content.Server.Gravity.EntitySystems;
 using Content.Shared.Acts;
 using Content.Shared.Alert;
 using Content.Shared.Coordinates;
+using Content.Shared.Gravity;
 using NUnit.Framework;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Map;