Dropbox folder name does not change after user name change

This patch does 2 things:

1) Makes the dropbox folder names unique (by including eid). It is not very uncommon that two students have the same name.

2) When a user changes first/last name the folder name is updated (next time the user opens the dropbox tool)

The patch is from our 2.8.2 but I have manually applied the changes to trunk to make a clean patch.