Dot op only supports matrix/vector args; other ndims must go through tensor.dot to ensure optimizations can be applied

1. make sure they are tuples
2. was checking if the max axis was > available dim, should have been
>= available dim

update unit tests to use new tensordot function, remove infer_shape tests for tensordot and tensordotgrad

the closing """ is ignored because of the #

ygrad still requires a transpose.