Attribute commit with the following changes...
- Able to delete elements that are not the root element
- Elements show the total assigned budget of children and compares
  with the parent elements budget
- All new elements are called new element for consistency and tidyness
- Working validation for activity attribute inputs
- Up button now displays correctly in the WBSElement overview
- It is no longer possible to create activities on elements that
  already have children
- It is no longer possible to create child elements on elements with
  activities