Add Adams method to appointment.methods.highest_averages

[andrewtavis]

The Adams method, as described on Wikipedia, is another highest averages method that could be implemented. This method has been implemented in voting, but lacks the allocation conditions that poli-sci-kit provide.

This issue would be to add this method to appointment.methods.highest_averages in a way that allows for minimum allocations, tie break conditions, majority bonus rules, and other conditional rulesets.