Rate the alignment of a contribution

[aahna-ashina]

Allow rating (attestation) of existing contributions.

Depends on #20 being implemented first.

[developerfred]

@aahna-ashina Does the rating have any impact on contributions or is it just additional information for contributor metrics?

[aahna-ashina]

@developerfred Yes, the average alignmentPercentage will be used for the final calculation. So other contributors can indicate that they think a contribution has lower, equal or higher alignment.

Example: If a contributor rates his/her contribution as "mostly aligned," while two other contributors rate it as "highly aligned," the final reward allocation weighting will be "highly aligned."