Repository and user management

[marcomass]

In the AdminPage add functionalities such as:

• remove all datasets of a user

• remove/close all "old" guest users and clean their disk space (also define policy for declaring old a guest user)

• remove an individual registered users and clean his/her disk space

• show more attributes of single registered users (e.g. registration date, used disk space, ...)

• Enable a user to request for an upgraded user category; consequently, an email should be sent to the user administrators listed (and easily updatable) in the system (but not publicly visible), and any of such administrator should be able to decide to accept or not the request and reply with a message to the user.

[marcomass]

• It is also useful to implement a functionality that allows a user to copy a dataset in his/her private repository to the private repository of another user, e.g., who required it, or alternatively (for publicly sharable datasets) to the public repository.
  This is a simple implementation of the very useful feature of sharing datasets among users.