Snippets Link should not be displayed if no public Gists exist!

[aadrian]

Snippets Link should not be displayed in header if no public Gists exist and the user is not logged in!

[takezoe]

Sorry, once I labeled this issue as "bug", but it wasn't.

A user who isn't logged in can find "New snippet" button there even if no visible snippets. This button shows the logged in form for a unlogged in user, but it can be conitinue to create a new snippet after logged in.