Subject lookup by UUID

[k1o0]

Currently the subject detail view has nickname as the lookup field

alyx/alyx/subjects/views.py

Line 67 in 7e1e139

lookup_field = 'nickname'

However, there may be more than one subject with a given nickname

alyx/alyx/subjects/models.py

Lines 203 to 205 in 7e1e139

	unique_together = [('nickname', 'lab'),
	('nickname', 'responsible_user')
	]

If we ever have two subjects from different labs with the same nickname, this would break some queries.