Hacky version of fitting spec support

[jonc125]

Will fix #182.

Also includes aspects of #137, #131.

It is hacky and completely untested! We should consider what needs to be done to tidy this up before merge, or possibly post-merge to enable cleaner review.

Some clear outstanding tasks, which may become separate PRs, in rough priority order:

• Add tests for the new features, especially around data upload & view.
• Fix any bugs revealed!
  • For some reason the dataset description is not being set
• Respect dataset visibility - e.g. at present anyone can overlay other users' private datasets. Possibly they can link their data to private protocols as well; I'm not sure.
• Link fitting specs to datasets (and via that to a protocol) so a 'fitting spec' protocol only contains the actual fitting specification. We definitely don't want to do that as part of this PR. It may get subsumed by longer term planning for how this will be architected, e.g. when FittingSpec becomes a concept in its own right.

[jonc125]

Added another issue I spotted to the description.

[skeating]

Currently the description is part of the file upload page. This is inconsistent with 'description' for other files upload which is on the creation page. It is probably an easier fix to move the field :-)

[jonc125]

Currently the description is part of the file upload page. This is inconsistent with 'description' for other files upload which is on the creation page. It is probably an easier fix to move the field :-)

Fine by me!

[jonc125]

I'm merging this to master so it can be deployed on scrambler and stop it being broken!