Updates on grid-based digital libraries with gLibrary

Description
gLibrary is the platform developed by INFN Catania to build, organize and access libraries of digital assets on a grid infrastructure. In the last two months, some new features have been added:
- Items can now be organized by collections. This is useful if there is a requirement to group together items belonging to different types. For example, a repository acting as a document library for several project can have a set of collections, one per project. Each collection groups together the documents, of different types, related to a given project;
- Array support for metadata attribute: one attribute can be set to a comma-separated list of values;
- Relations support: each object can have now relations with other objects of the same repository;
- Web upload: users can upload new items directly to the grid storage elements from the browser, having their X.509 certificate loaded in their browser. There is no more need of java applet to handle uploads.