Add permission system for requesters

[hltcoe-bot]

Currently, all requesters are superusers and can edit or publish to all projects. As the set of requesters grows, we want to remove superuser access and need a permissions model for access to project and batch admin pages.

In a comment on #200 charman suggests the following:

Here is an initial set of proposed permissions:

• should be able to create new Projects
• should be able to modify Projects they created (currently tracked using Project.created_by)
• should be able to modify Projects they have been granted modification-level access to by other Requesters
• should be able to grant modification-level access to other Requesters for Projects they have modification-level access to
• should be able to publish Batches for Projects they created (batch creator currently tracked using Batch.created_by)
• should be able to publish Batches for Projects they have modification-level access to

We may also want to add:

• should be able to publish Batches for Projects they DO NOT have modification-level access to

Poster: Cash Costello id: 202

[hltcoe-bot]

mentioned in issue #179

Poster: Craig Harman

[hltcoe-bot]

mentioned in issue #223

Poster: Craig Harman