Create a page listing all the available repositories

[mssola]

This comes directly from Docker Hub's "Explore" feature. So, for example, there would be a link on the top navigation bar that when clicked it will redirect the user to a page where all the repositories that are visible to the current user are listed.

Note that this would also apply for non logged-in users when the issue #279 gets implemented. For non-logged in users, only "open" repositories would be listed.

[mssola]

Closing since this has been recently implemented and I didn't double-check ...