Catch error if scipy import fails

- we still need to implement a basic replacement in case scipy is not available

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Fix module imports in unit tests

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Fix some issues with unit tests

Signed-off-by: Stefan Marr <git@stefan-marr.de>
Let's use Python 2.7 as the standard

Signed-off-by: Stefan Marr <git@stefan-marr.de>