Show collections on generic_file view

This enhancement shows the list of collections of which this file is a member, on the generic_file view.  Same info as is now being rendered on each item in the My Files list in the dashboard.

CLA is hopefully coming within the next few days... apologies that it's taking so long.
I think this might be more idiomatic:

```erb
<% if @generic_file.collections.blank? %>
```