[Bug] Expired session should show a dialog or login page on pageload

[gimmic]

Bug & Feature Request

Question	Answer
OS version (server)	CentOS 7
TheHive version / git hash	4.0.0-1
Package Type	RPM
Browser type & version	Chrome

Problem Description

If left open and the session expires, clicking a menu nav option allows the page to 'load' with zero content. This is confusing as it appears you're still active but the site is missing content.

Steps to Reproduce

1. Login and open content.
2. Let sit idle beyond the timeout.
3. Click on 'Alerts' along the top ribbon nav.
4. Alerts appears to load but is blank/empty. This is because the session is invalid and no content is loaded. Refreshing the page causes the login page to show up properly.

Possible Solutions

Check for valid session before loading cache/returning results in some fashion. Direct to the login page.