Bump version to 0.7
Release notes for version 0.7
Fix gem timestamp, bump version
New cache mode (:all) to cache everything.

Also, change string literals to ' for
non-interpolated strings. Cache logger specifier.
Make the no-op persister work
Make the migration SQL code ANSI compliant
Search in-memory for the items to return.

Instead of going to the persister, search
the just retrieved/loaded entities in memory.
This saves a query for the persister and also
decouples the retriever from the persister to
make it work independently.
Add the ext_uniq field in case the persister does not