Move fix to storage layer

Don't know if this is the better way but works.

src/Artemis.Storage/Repositories/ProfileCategoryRepository.cs

@@ -41,6 +41,7 @@ namespace Artemis.Storage.Repositories
 
         public ProfileCategoryEntity IsUnique(string name, Guid? id)
         {
+            name = name.Trim();
             if (id == null)
                 return _repository.FirstOrDefault<ProfileCategoryEntity>(p => p.Name == name);
             return _repository.FirstOrDefault<ProfileCategoryEntity>(p => p.Name == name && p.Id != id.Value);

src/Artemis.UI/Screens/Sidebar/Dialogs/SidebarCategoryCreateViewModel.cs

@@ -50,7 +50,7 @@ namespace Artemis.UI.Screens.Sidebar.Dialogs
 
         private bool BeUniqueCategory(SidebarCategoryCreateViewModel viewModel, string categoryName)
         {
-            return _profileCategoryRepository.IsUnique(categoryName.Trim(), null) == null;
+            return _profileCategoryRepository.IsUnique(categoryName, null) == null;
         }
     }
 }