* [side nav] redesigned it: added a new item 'Files', and made 'My Libraries' and some other items as its sub nav items
* ['Files'] added new page 'Files'(added 'My Libraries' to it)
* ['Files'] added 'Shared with me' to it
* ['Files'] added 'Shared with all' to it
* ['Files'] added 'Shared with groups' to it (removed 'details' for 'department')
