Unpin pillow

[bjlittle]

This PR adds the relevant images after unpinning pillow.

[pp-mo]

This is not the right way, I think.
The 18-ish new files are all duplicates of the old ones with different names (as the hashes have changed).
But that means that the old files no longer have names which match their hashes, which breaks the logic
-- which is what the test is for + why it fails.

I think you must rename them, not duplicate.
But it means changing Iris too : we need the SHAs to change in Iris imagerepo.json, at the same time as unpinning pillow in Iris travis, and updating its reference commit for test-iris-imagehash download. They all have to happen at once.

[pp-mo]

Also... there are a lot more than 19 failures.
This is not a trivial exercise, or we would have done it instead of pinning #30
😟

[bjlittle]

@pp-mo this was a work in progress... and just need further analysis

i've jumped though these hoops before... i'll restart this pr from afresh, thanks