https://github.com/bountysource/frontend/issues/51

Create Receipt page, display after pledge / bounty

- Added receipt pages for pledges/bounties
- Added pledge / Bounty amount & info (fundraiser/issue details)
- Added "Share this" call to action with URL of issue to spread around and share on Facebook, Twitter, GitHub buttons. Note: the bounties page currently has a busted link, as we don't know the bounty ID that was added to the system after successful payment.
- Added "Other issues/fundraisers you may be interested in." Three most recent fundraisers, three most popular issues based on tracker.
- Added "Follow this project" button

Note: receipt page data is keyed off querystring parameters due to the opaque nature of the payment API. Some functionality (such as the anonymous/public button) is disabled due to not having the id of the newly created resource.