message: Looked up animation resource id from name
  If null returned default. The lookup returns 0 if name not found so that's no animation, which seems fair
diff: @@ -50,12 +50,11 @@ public class NavigationModule extends ReactContextBaseJavaModule {
  int currentCrumb = mIntents.size() - 1;
  if (crumb < currentCrumb) {
  final Intent intent = mIntents.get(crumb);
  - currentActivity.navigateUpTo(mIntents.get(crumb));
  for(int i = crumb + 1; i <= currentCrumb; i++) {
  mIntents.remove(i);
  }
  - final int enter = this.activityCloseEnterAnimationId;
  - final int exit = this.activityCloseExitAnimationId;
  + final int enter = this.getAnimationResourceId(null, this.activityCloseEnterAnimationId);
  + final int exit = this.getAnimationResourceId(null, this.activityCloseExitAnimationId);
  currentActivity.runOnUiThread(new Runnable() {
  @Override
  public void run() {
  @@ -75,8 +74,8 @@ public class NavigationModule extends ReactContextBaseJavaModule {
  mIntents.put(nextCrumb, intent);
  intents[i] = intent;
  }
  - final int enter = this.activityOpenEnterAnimationId;
  - final int exit = this.activityOpenExitAnimationId;
  + final int enter = this.getAnimationResourceId(null, this.activityOpenEnterAnimationId);
  + final int exit = this.getAnimationResourceId(null, this.activityOpenExitAnimationId);
  currentActivity.runOnUiThread(new Runnable() {
  @Override
  public void run() {
  @@ -86,5 +85,13 @@ public class NavigationModule extends ReactContextBaseJavaModule {
  });
  }
  }
  +
  + private int getAnimationResourceId(String animationName, int defaultId) {
  + if (animationName == null)
  + return defaultId;
  + Activity currentActivity = getCurrentActivity();
  + String packageName = currentActivity.getApplication().getPackageName();
  + return currentActivity.getResources().getIdentifier(animationName, "anim", packageName);
  + }
  }
  