Update pynwb version

[ageorgou]

We should move to at least version 1.3.1, which includes some fixes and features of interest:

• Reading extensions Are namespaces/extensions cached in example files? #26
• Multiple channels Red and green channels on the same imaging plane #14
• Device description Devices missing from signatures #27
• (but see also an issue with manifold compression Replace manifold #63)

pynwb 1.3.1 uses schema version 2.2.4. I have read files that we created recently with schema 2.2.2, and the changelog does not show any big changes between them. In fact, it may be best to move to pynwb 1.3.2, which includes some small schema fixes.

One change stands out in schema version 2.2.0 (although we are already using that):

Changed dims of ImageSeries from (frame, y, x) to (frame, x, y) and (frame, z, y, x) to (frame, x, y, z) to be consistent with the dimension ordering in PlaneSegmentation.
So our files may be valid, but does this mean we should switch how we call the ImageSeries constructor or not?

Note that the just-released 1.4.0 uses a new major version of hdmf, which introduces many changes in the signatures (mostly small ones from accidental use so far...).

[ageorgou]

Updated to 1.3.2 as part of #65.