ROL-869: Weblog settings page throws exception on save if weblog is using shared theme

[Dave Johnson]

Allen,

I think the fix for this one is to allow website.defaultPageId to be 
null. Because, when using a shared theme there is no need to track the 
ID of the theme's default page within the weblog itself.

http://opensource2.atlassian.com/projects/roller/browse/ROL-869

Any advice on this?

- Dave