Added Google authentication using microsoft.owin.security classes (mvc 5)
Added html title retrieval on posting links.
Authorization support:

- Require "LinkViewer" role to view links
- Added basic management views to add users to roles
Renamed "RoleMissing" page to "AccessDenied". Added RolesController restriction that user must have "Admin" role
Added authorization support to Post link API (Linx-Access-Token header)
Show missing role name on Access denied page
Correctly return link PostedAt date when posting
More robust HTML title fetching