* User reportlab to render the submissions into pdf

* Improve layout and look of submissions and pdfs
This makes headings render smaller than the questions within rich text fields

* Enable h1 tag in bleach
Based on changes to how headings are rendered this is now more reasonable.

* Update the payment request tables to simplify for type of user

* Improve copy on modal forms and hide create project if not possible

* Improve wording to project around uploading contract

* Vary the name of the document select form so that it doesn't clash

* Make sure get_object returns the underlying instance not the form instance

* Improve the visuals on the project page when payment requests active

* Defer loading of category object until we reference it
  * improved performance when iterating over many submissions which never look up category

* Convert to using a lazy paginator in order to avoid expensive counts
  * Table querysets are complex and doing count on this is very expensive and this can reduce /all page load times by ~50%

* Fix the approve contract and approve forms

* make sure we can share error messages with the user

* Make the choose file link intelligent

* Update the document chooser to user the model form and update tests

* Update the messaging to be more in line with other messages

* Make sure we tick the documents when all uploaded

* Tidy up the visual components (contract/links) on the detail page

* Tidy up how forms are contributed to the parent class

* Improve the delegated form base behaviour

* Refactor to remove the payments mixin

* Give the detail and edit views of the payment request their own view

* Remove the download link and change to a view

* Refactor the views to be better sorted

* Improve the interaction experience for payment requests and add activity

* Improve look of payment table to be a bit more bulked out

* Allow passing a path to the slack notification system

User.get_absolute_url was pointing at the wagtail admin which would expose the
admin urls to users on the frontend. The admin view is not necessarily the
"canonical" view for the user so should not be relied upon in the long run.

By allowing passing of a url to the slack notifier we allow the emitter to point
to the destination regardless of the more front end focused model method.

* Cache the image urls for tables
* Prevent instantiating the whole stream_value if we dont need to
* Remove an unused include in the submissions template
* Tweak pre-fetching to fetch the correct things
* Defer checking of user in activity until we are sure we need to

* Refactor the private storage class to be more generic
* Update the views to serve the project documents through the urls

* Link up the CREATED_PROJECT and UPDATE_PROJECT_LEAD to the activity
* Add tests for the new activities from project

ref #1329

'#860 WIP saving reviewers in batch from submission list page, includes new DelegateableListView class

Rename some of the custom and requeried fields when creating/editing application forms. Remove the other section and merge what with custom.