check if cached annotation/studyset is different from uploaded one.

[jdkent]

this way we will not pollute the database with a bunch of repetitions.

[adelavega]

Need more detail here to determine if important.

[jdkent]

The neurosynth-compose api takes snapshots of studysets and annotations for every meta-analysis run, we could more efficiently store the meta-analysis and annotations if there was a check to see if the studyset/annotations changed between meta-analyses, this way we could more easily separate whether multiple meta-analysis runs had the exact same inputs, or if the inputs changed from one run to the next.

[jdkent]

This will be tied with #1248, once people can reliably update their studysets, they will want to run meta-analyses with updated studysets (the caching may be getting in the way).