Better ini error message when ini file is not in the run folder

[arthurmensch]

All in the title.

The modified file is not tested (which is bad), but much bravoure would be needed to address this terrible lack.

running python examples/easy_start/nipype_preproc_spm_auditory.py from root now yields:

Traceback (most recent call last):
  File "examples/easy_start/nipype_preproc_spm_auditory.py", line 49, in <module>
    subject_data = do_subjects_preproc(jobfile, dataset_dir=dataset_dir)[0]
  File "/home/arthur/.conda/envs/py27/lib/python2.7/site-packages/pypreprocess/nipype_preproc_spm_utils.py", line 1529, in do_subjects_preproc
    ' as the .ini file' % subject_factory)
IOError: Could not load spm_auditory_preproc.ini, please make sure to run your script within the same folder as the .ini file

[bthirion]

LGTM.

[dohmatob]

LGTM2, merging.