Update dogpile.cache example to be compatible with baked query.

Update dogpile.cache example to be compatible with baked query.

Updated the dogpile.caching example to include new structures that
accommodate for the "baked" query system, which is used by default within
lazy loaders and some eager relationship loaders. The dogpile.caching
"relationship_caching" and "advanced" examples were also broken due to
:ticket:`4256`.  The issue here is also worked-around by the fix in
:ticket:`4128`.

Note that this recipe requires
I3f86fcb12a6a9a89aa308b335e75c25969bcc30e in order for the
"advanced" example to work.

Change-Id: I9d35417f1d6c1906555583b8225d3da7f81736f7
Fixes: #4258