5.1.0.4 model changes revised

[alancleary]

Unlike the 5.1.0.4 model changes PR, this PR will ultimately be merged. I'm opening it now as a draft to keep track of specific changes that will need to be scrutinized during the review.

Specific changes:

• Is the InterMine data source function getPublicationsForDataSource implemented correctly? See commit b4a9d6d482b76651d5f58b40ca28104980b9c20e
• Is the InterMine data source function getIntronsForGenes implemented correctly? See commit f4149304c52e6fa87e8b2d9b19ac3360d7110d44