Single-user mode

Single-user mode

New configuration options to define a single-user mode. This hides
most of the "community" pages, like the public timeline and groups.
The main user's timeline becomes the main page, and most other URLs
are changed.

Switching back and forth between 1-user and multi-user mode is
probably hazardous.

Squashed commit of the following:

commit d814aa5c92d14a27a12baba7893f3f8bf63f1d08
Author: Evan Prodromou <evan@status.net>
Date:   Tue Jan 26 00:17:27 2010 -0500

    don't show inbox and outbox in single-user mode

commit 47f19b9523a7015d4c6e460b73ea32c839e00aa1
Author: Evan Prodromou <evan@status.net>
Date:   Tue Jan 26 00:15:22 2010 -0500

    show correct URL for logo in single-user mode

commit 552010cffc33eadbc512ec5a67619dbc2015239a
Author: Evan Prodromou <evan@status.net>
Date:   Tue Jan 26 00:15:06 2010 -0500

    make singleuser its own config section

commit 786ab260a3ca172e57b555c75ca10946d8f258a1
Author: Evan Prodromou <evan@status.net>
Date:   Tue Jan 26 00:05:19 2010 -0500

    make single-user mode work

commit 5b21d7309b3a8dd5a4e0f29aea76f7897f1818b1
Author: Evan Prodromou <evan@status.net>
Date:   Mon Jan 25 23:45:55 2010 -0500

    add single-user mode