Since you are using <sql> liquibase cannot parse or know that 1 and 0 are going into a boolean column to do any sort of conversion.
You could use changelog parameters like:
NSERT INTO Variable (id, version, core, created_on, description, name)
VALUES
('ce02bb08-ae7d-4f9c-a94b-bc2a7fcd982c', ${false}, ${true}, '2013-08-29 14:55:09', 'desc 1', 'name 1'),
('53c50b45-8b3b-4061-9594-b1fe3826080f', ${false}, ${true}, '2013-08-29 14:55:09', 'desc 2', 'name 2');
and set them based on the db in the header:
<parameter name="false" value="1" dbms="mysql"/>
<parameter name="false" value="false" dbms="derby"/>
Or you can switch to using the <insert> tag where you can specify the "type" in the column tags as boolean and then liquibase can do the conversion.
Nathan