Adds data upload and sharing agreement template to the project files page.

[lamawmouk]

This is the first step to add a data upload agreement under the project files page.

The changes include:

• Adding a template to allow users to complete a data upload agreement.
• Adding a model to store users responses to the form.

Here is the example of the data agreement form that users would fill in:

The next step is to add a modal, and update views and forms to allow users to submit and save responses into the database.

[lamawmouk]

The data upload agreement framework was tested after filling all the sections in the project and not the data upload agreement. Users are notified that they have not completed the data upload agreement in two places :

1. View the project preview
   
2. Before Project Submission

If the data upload agreement has been completed the user is notified as shown below:

Below is the form that the users have to complete:

[tompollard]

Superseded by https://github.com/MIT-LCP/physionet-build/pull/2479