find() accepts conditions that are not expressions

[Edwin Grubbs]

If I have a storm class with an attribute named similarly to a storm attribute, it can be fairly easy to write a bad conditional. For example:

class MyTable(Storm):
    _foo = Int()
    @property
    def foo(self):
         ...

store.find(MyTable, MyTable._foo == 9) # good query: WHERE foo=9
store.find(MyTable, MyTable.foo == 9) # bad query: WHERE FALSE

It would be nice if storm raised an exception or a warning when something that isn't a storm expression is passed in as a condition.