Add M-Changa app

- Add mchanga app
- Add models to store M-Changa payments
- Add adapter to read M-Changa API
- Add management command to sync with API
Add Mchanga app + admin + front end
Update donated amount
Add 'Lipa na Mpesa' button on project page.
Add a IPN url that receives status updates.
Show favorite Campaigns on Cheetah start page.

CLUB-880 #resolve
New Bb that has the right templating
Merge pull request #1536 from onepercentclub/feature/club-885-mchanga-admin

Feature/club 885 mchanga admin