Fixed situation where compile lock would not be released after failing to create a temporary work dir

'Added more test for cuda_ndarray.zeros() and make it raise an appropriate error when it receive no input.'

We may change that in the future.

Fixed test-suite error caused by nosetests trying to run a method that was not intended to be a test by itself

Removed recently added extra argument convert_as_array to TensorType.values_eq, since it is not needed as Pascal pointed out

Fixed crash introduced in fdc11984cb9d when using e.g. a list as input to a theano function instead of an ndarray

Fixed crash when adding to C cache a Composite Op created before adding / modifying some config options

- Added some doc about the identity, commutative and associative fields
- Fixed crash in filter function when using NaN values