Save 'backers' data in project profile

Saving the list of backers in the
project data allows us to make views that
show us the profiles of a patron's backees.
Edit: Show list of all contributions

Add a new page, /edit/contributions, for showing a
logged-in patron's contributions.
Edit: Contributions: Basic data formatting

Format the data shown on the /edit/contributions
page in a basic, readable fashion.
Header: Link to the logged-in patron's page