Improve the citations list

The citations list in [here](https://github.com/InsightSoftwareConsortium/insightsoftwareconsortium.org/blob/master/static/citations-visualization/ITKBibliography.bib) requires some work:
- The encoding of some characters is incorrect (see the question mark diamond characters in `johnson2015itk` for example)
- The keys to the publications are not consistent, like "authorYearVenue" (e.g. `beare2011citk`, `RN826`).
- Some fields do not have any meaningful information (e.g. https://github.com/InsightSoftwareConsortium/insightsoftwareconsortium.org/blob/master/static/citations-visualization/ITKBibliography.bib#L72)
- The entries for each type should be the same and complete, and be sorted in the same way for the sake of readability.
- The publications in the `To Appear` category (see https://insightsoftwareconsortium.org/citations) were surely published by now. These entries need to be updated.
- It is probably best to remove the abstracts, as they take up a non-negligible amount of space that makes it difficult navigating across the file.
- Not sure about how the `type` field (e.g. https://github.com/InsightSoftwareConsortium/insightsoftwareconsortium.org/blob/master/static/citations-visualization/ITKBibliography.bib#L71) is used; for most cases the BibTeX entry type already defines the type, so best may be to leave it blank everywhere for the sake of consistency (?).
- The articles listed in the [ITK `README`](https://github.com/InsightSoftwareConsortium/ITK/blob/master/README.md#citation) should be consistent to the data in the list or added if missing.