Output contribution list for Candidates without committee rows

[tdooner]

For candidates without entries in the committees spreadsheet tab, we still want to output their contribution list. The problem is, we store their contribution list on the Candidate instead of their associated committee. We also muddy the waters by saving a calculation called total_contributions which is calculated differently between Candidates and Committees.

This commit:

• Renames the calculation for the total of the contribution list to contribution_list_total and adds fallback logic to mimic the previous implicit overwriting behavior
• Adds a committee_data method to Candidate to output the calculations related to the committee.

[tdooner]

@mikeubell I'm just going to merge this - it looked pretty good locally. We can check out the results when the build runs today.

[mikeubell]

This fails to calculate total_small_contributions for a candidate where there is no entry in the committees table for that candidate. See line 52 in candidate_contributions_by_type.rb