ui: Add tooltip when hovering long names

If the storage pool or network names are very long strings, they are
trimmed (e.g. "myverylongnetworkname" becomes something like "myverylo...").
If multiple names have the same prefixes, the user will not be able to
distinguish them.

Add tooltips displaying the full names when hovering storage pool and
network names.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>