Fixes attach state management when a controller is pushed while the Activity is paused. (Fixes #303)

conductor/src/main/java/com/bluelinelabs/conductor/Controller.java

@@ -8,7 +8,6 @@ import android.content.IntentSender;
 import android.content.res.Resources;
 import android.os.Build;
 import android.os.Bundle;
-import android.os.Handler;
 import android.os.Parcelable;
 import android.support.annotation.IdRes;
 import android.support.annotation.NonNull;
@@ -732,8 +731,8 @@ public abstract class Controller {
         return false;
     }
 
-    final void setNeedsAttach() {
-        needsAttach = true;
+    final void setNeedsAttach(boolean needsAttach) {
+        this.needsAttach = needsAttach;
     }
 
     final void prepareForHostDetach() {

conductor/src/main/java/com/bluelinelabs/conductor/ControllerChangeHandler.java

@@ -218,6 +218,10 @@ public abstract class ControllerChangeHandler {
                             ((ViewGroup)fromParent).removeView(fromView);
                         }
                     }
+
+                    if (handler.removesFromViewOnPush() && from != null) {
+                        from.setNeedsAttach(false);
+                    }
                 }
             });
         }

conductor/src/main/java/com/bluelinelabs/conductor/Router.java

@@ -577,7 +577,7 @@ public abstract class Router {
     void prepareForHostDetach() {
         for (RouterTransaction transaction : backstack) {
             if (ControllerChangeHandler.completeHandlerImmediately(transaction.controller.getInstanceId())) {
-                transaction.controller.setNeedsAttach();
+                transaction.controller.setNeedsAttach(true);
             }
             transaction.controller.prepareForHostDetach();
         }