Fixed issue #610

Signed-off-by: Marc de Jonge <marc.dejonge@tno.nl>
Merge pull request #611 from marcdejonge/master

Don't treat name as a format string
Use different tmp files for each test method

Using the same file created problems on windows when it sometimes could
not be deleted.

Signed-off-by: BJ Hargrave <bj@bjhargrave.com>