Update allocatedRN value: shorten process time

- new attribute on each node: additionnalPoolShares to store any poolshare that has been created on a particular node
  this happens when user changes the pool value
- when updating alocatedRN we sum the alloc of the current poolshare and any additionnalPoolShares
  this is much faster than parsing all poolshares on the server
- FIX: when deleting a node, we alse delete additionnal pool shares to keep server data consistent