Intersphinx entries are keyed off by URL, not by name. The recent

version bump resulted in us having two entries pointing to the same URL,

preventing intersphinx lookups based on prefixes from working correctly.

Instead of maintaining an older 0.10 docset, the intersphinx entries and

references in the 0.10 beta docs have been updated to point to the 1.0

docs instead.
The 0.10 beta 1 docs have also been updated to use

default-intersphinx, allowing us to remove unwanted prefixes.
The non-existent Djblets 0.9 intersphinx inventory has also been

removed.

Built the docs. Intersphinx references worked, and there were no build

errors.