better data sanity checks

[mikeshultz]

Traceback (most recent call last):
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/core/handlers/base.py", line 132, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/views/generic/base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/views/generic/base.py", line 89, in dispatch
    return handler(request, *args, **kwargs)
  File "/home/mike/dev/doto/doto/views.py", line 53, in get
    objs = Task.objects.filter(profile_id = request.GET.get('profile_id'), complete = False)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/query.py", line 679, in filter
    return self._filter_or_exclude(False, *args, **kwargs)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/query.py", line 697, in _filter_or_exclude
    clone.query.add_q(Q(*args, **kwargs))
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/sql/query.py", line 1301, in add_q
    clause, require_inner = self._add_q(where_part, self.used_aliases)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/sql/query.py", line 1328, in _add_q
    current_negated=current_negated, connector=connector, allow_joins=allow_joins)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/sql/query.py", line 1191, in build_filter
    lookups, value)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/fields/related.py", line 1740, in get_lookup_constraint
    lookup_class(target.get_col(alias, source), val), AND)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/lookups.py", line 96, in __init__
    self.rhs = self.get_prep_lookup()
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/lookups.py", line 134, in get_prep_lookup
    return self.lhs.output_field.get_prep_lookup(self.lookup_name, self.rhs)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 727, in get_prep_lookup
    return self.get_prep_value(value)
  File "/home/mike/virtualenvs/doto/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 985, in get_prep_value
    return int(value)
ValueError: invalid literal for int() with base 10: 'undefined'