Identity.deleteWithoutCommit(): Use mRequestURIString

- The upgradeDatabaseFormatVersion5() which is mentioned in the added
comment will be added in a following commit.
Identity.startupDatabaseIntegrityTest(): Use mRequestURIString

Now not mRequestURI == null but mRequestURI != null is an error since it
is replacd by mRequestURIString and thus should always be null as
specified by its  JavaDoc.
Identity.storeWithoutCommit(): Use mRequestURIString