Make Person and Position's __unicode__ methods consistent

When tracking down problems with Person and Position objects
it can be confusing that they use different representations
of the person's name.  This commit switches Person to also
use legal_name.  This has the advantage that you should never
cause another query by calling Person's __unicode__ but the
disadvantage that the admin interface will show the legal_name
in various places instead of the (probably better-known)
alternative name that's marked as the one to use.
Add a script to remove some duplicate aspirants

Because some name matches that were missed, we've ended up with
some duplicate aspirants.  In a previous commit I introduced a
script that adds some alternative names for the correct aspirants;
this script checks within each race for any candidate's name that
matches an alternative name of another - in those cases the
other aspirant is removed.
Correct a typo in the corrections file
kenya_apply_updates: ignore missing positions

This is useful so that kenya_apply_updates can be re-run after
duplicates have been pruned.
Remove commented-out notes