Disable the expensive validation in COBranch and COSQLiteStorePersistentRootBackingStore until it can be rewritten in a less wasteful way. These were just looking for 1. COItem type/value mismatches (could be enforced inside of COItem), 2. broken inner references, 3. committing item graph with no root, or a non-existent root.  We need tests that trigger these failure cases

git-svn-id: http://svn.gna.org/svn/etoile/trunk/Etoile/Frameworks/CoreObject@10426 7b3f36aa-e6db-49c1-8b4c-66eac1997e64