old MR notebooks have multiple problems

[KrisThielemans]

The older notebooks (not those in the interactive folder) were stripped too much and we get an error when opening them (see the process in #20).

They also need changing of petmr_data_path(...) with examples_data_path('MR').

However, I suspect that the notebooks in https://github.com/CCPPETMR/SIRF-Exercises/tree/master/notebooks/MR shouldn't really be there anymore and are superseded by those in interactive. @ckolbPTB @johannesmayer @DANAJK could you confirm that these are safe too delete?

I'm not sure what to do with those in tools. acqh5info might contain things that are now elsewhere. im5info uses h5py and seems interesting (but could do with some more info). @DANAJK, do we keep these ?

[paskino]

I was in the process of testing the notebooks.
I fixed the notebooks in MR #30

Except from this the others seem to work.

[KrisThielemans]

what's the problem with the remaining one?

[KrisThielemans]

I've created a separate issue for the remaining problem. #31