Fix location of image in sasview-api docs

[llimeht]

Updating the location of the BatchGridClass.png image permits sphinx to generate the PDF once more. (A slightly prettier relative path might also be possible...)

[pkienzle]

Haven't had a chance to look into implementation details, but we should not be encoding the structure of the sphinx doc tree into the documentation for the individual perspectives. If one perspective is referencing media from another perspective, we just need to make sure that we walk up the tree enough that we can walk down to the sister perspective. Maybe removing the parent reference .../user would accomplish the same thing?

[pkienzle]

I'm not seeing the problem with the latex builds, and the path seems correct for the location of the files within the source-temp tree created by the build_sphinx.py. Please explain why you need this patch a little better, or close this pull request without merging.

Note that for building the docs, make does not work. You need to use build_sphinx.py.

Note also that the docs incorporate some of the docs for sasmodels and bumps, so they need to be in sister directories when the build starts, with docs already built for those packages. I can see this causing difficulty for your Debian build if you are treating sasmodels, bumps and periodictable as separate debian packages (sorry!) but we would otherwise not be able to build a coherent set of documentation for standalone sasview.

[llimeht]

This looks like it was a side-effect of trying to deal with the difficulties of stitching together the 3 different documents. Sorry for the noise.