[patch] selectBy(nonexistantcolumn=foo) passes silently

When doing a query on a table, for instance:

Foo.selectBy(food="bar")

where 'food' is a typo, and 'foo' is the correct column
name, no error will occur, and this is equivilnet to:

Foo.select()

Attached is a patch to both dbconnection.py and
tests/test_select.py, adding an exception to the code
for the case where unexpected kwargs are passed, and a
test for that behaviour.