Hide the sidebar if it's empty.

When updating the view check to see if the sidebar
contains any visible children elements. If not,
hide it.
Merge master into 309-expand-content-when-sidebar-empty
[#309] Fix rendering of fields widget in IE7.
[#309] Small JS fix for IE7.

Extra comma in object literal removed.
Merge pull request #309 from okfn/309-expand-content-when-sidebar-empty

Expand main content view if sidebar is empty