Better Formating for source description

- Convert github markdown fields
- Source item description formating for github markdown
- Fix incorrect github url
- Fix bug where urls didn't use cleaned urls
Add due date in edit view
Include additional identifying information

As a user I find it difficult to know which source is realted to what
trello board or github repo.

trello = [Psyc E-1430:This Week], github = [Simplepearl]

- Add group model
- Add board from trello api
- Add repo from github api
- Don't fetch sources on load
add source item group to templates
Issue #37 - Show additional information for sources

As a user I find it difficult to determine which sources i should be
working on just based on the title

- Better formatting for source description
- Include additional identifying information trello = [Psyc E-1430:This Week], github = [Simplepearl]
- Add identifying information in edit view
- Add due date in edit view