deposit: test case fix

* Fixes issue with module level legacy cache.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
base: MathJax removal and assets updates

* Removes MathJax from assets as we are using CDN instead.

* Updates some other assets.

* Adds support for zenodo-assets package if installed.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>