show user, groups and contacts info (WIP)

when selecting a treeview node
simplified also handler for double click
menu restyle, some icons remaked, and tabs restle (WIP)
fixed load in click handler
allow some empty parameters in view mode
tabs restyle and item-block class added
do not print empty <h3>'s if no titles defined
Merge branch 'jacalvo/view-user' into jcarrion/ui-restyling
treeview restyle (WIP)
left area of tree view finished
always edit instead of view when clicking
Merge branch 'jcarrion/ui-restyling' of github.com:Zentyal/zentyal into jcarrion/ui-restyling
treeview restyle
remove delete button as now nodes are directly editable when clicking
do not show modules configuration block if no components

and add title also to edit group
Added better 502 error page for nginx with redirect when apache is ready
treeview images and style polishing
foldable sections restyled
some minor fix
treeviw restyle for contacts