attempted to fixed shit that Andre broke
merge
merge
merge some more patches from features/type_checking...

...to make unit tests and Ole happy.
snapshot
Merge branch 'devel' of github.com-oleweidner:saga-project/saga-python into devel
fixed bug in SLURM working_directory logic
another fix
merge from devel
more type checks, small fixes

There are no type checks on utils, yet -- not sure if those are needed / useful / ...
Otherwise the tests are complete for the API layer AFAICS.