Fetch graph data and format pie chart for CampaignContributions

[otech47]

• [ ] Open popup, click a candidate, click leftmost contributions segment icon -> campaign finance data loads properly with Total Raised, Total Spent, On Hand values and donut chart divided by source of contribution
• [ ] Load campaign finance data, hover over a portion of the donut chart -> Percentage, total contributions and name of course appears in a popup overlay next to the chart
• [ ] Open popup, click a candidate, click leftmost contributions segment icon, wait for loaded campaign finance data, click the back button in the top left, click a different candidate, click leftmost contributions segment icon -> new candidate's campaign finance data loads properly with Total Raised, Total Spent, On Hand values and donut chart divided by source of contribution
• [ ] Open popup, click a candidate, click leftmost contributions segment icon, wait for loaded campaign finance data, click the back button in the top left, click the same candidate, click leftmost contributions segment icon -> the same campaign finance data of the candidate loads properly with Total Raised, Total Spent, On Hand values and donut chart divided by source of contribution
• [ ] Open popup, click a candidate, click leftmost contributions segment icon, wait for loaded campaign finance data, click the back button in the top left, click a different candidate (do NOT click left segment), click the back button in the top left, click the 1st candidate selected -> the same campaign finance data of the 1st candidate loads properly with Total Raised, Total Spent, On Hand values and donut chart divided by source of contribution

[otech47]

https://www.opensecrets.org/races/summary.php?cycle=2016&id=FLS2

@sinnott-balin