Initial draft of the ground station web app

Takes the Angular seed project, and updates it with html taken from
Bootstrap. I've then renamed the first page to /telemetry, and renamed
the associated controller accordingly. Updates the page so that it displays
something, even if that's just to show that it doesn't yet have any data.
In the next commit, I'll update it so it picks up data from the database
server.
Updates database server so we return the latest object

Rather than an array containing one entry, that being the latest object.
From the semantics of the url, you would expect to receive an object
rather than an array. We don't yet handle the case where the database
contains no entries - I've added a TODO for now.
Updates web app to query database service for latest data

The web app queries the service every second. The server has been updated
to allows CORS, otherwise GET requests from the web app fail.
Updates web app so it handles empty data from the server

In the server, we now return an empty object if the database doesn't have
any entries. On the web app side, we check whether the data is empty.
If it is, we display the "No data" labels. Adds unit tests to test this
behaviour.
Merge branch 'features/web-app'