Make sure all apps use the trust proxy setting

Without this setting enabled the apps get the incorrect 'req.protocol'
and therefore generate http urls even when the connection has come in
over https.

The hosting-app, instance-app and dev-helpers all have the setting set
individually because they are top level express applications. Other
applications are created using the express-inherit module, so we just
inherit the setting from the parent application in that case.
Make sure API urls use the correct protocol

The API app is mounted inside another app, which in turn is mounted
inside a parent, so at the point the API is mounted the parent
doesn't have the trust proxy setting, so to fix the urls in the API
I've set some properties on the request object in the parent app,
which does correctly inherit the trust proxy setting.
Merge branch 'all-apps-should-trust-proxy'
Fix API url on API page
Add .vagrant directory to .gitignore
Show posts and post count on the instance homepage
Add virtual url property to post schema
Fix post display on homepage
Add initials method to Post

This doesn't really make sense for a post, need to come up with
something better to put here.
Add posts app using generic document

This allows posts to be listed at /posts in the UI.
Rename post partial used in organization view

The view post view is called post/view.html by default. The partial in
the organization view/form had a conflicting name, so I've renamed that
so we can use the default name for the actual post view.
Add page to view individual post

This shows the post label, role and area name.

Will also need to add the person/organization that these are attached to
if relevant.