ParserTests: fix `bits` column in uploaded images for test cases.

ParserTests: fix `bits` column in uploaded images for test cases.

When running parser tests on a sqlite3 database, the insertion of the
djvu image before running the test suite will fail because `NULL` is not
a valid value for the `bits` column of the `image` table.  This will
cause the test suite to eventually fail, since {{NUMBEROFFILES}} differs.

Test uploads show that `bits` is usually set to 0 for both SVG and
DJVU uploads, so fix this (in both the standalone test runner and the
phpunit test runner).

Change-Id: I8689a547d34035534723e87c4c2680c4e67245f2