STY: various blas/test_blas fixes

Fix missing pydot (tests/error message)

Dot22 complex still w pep8 errors but Fred's busy.

fixed cifar example.

Tensor cast error is clearer and has helpful hint.

To avoid confusion, 'array' usually refers to numeric (numpy) data,
while 'tensor' often refers to symbolic (theano) objects.

Switched order of exception arguments to first say that there is a bad
input in some position, before explaining why it is bad.

Added a 'size' attribute to tensors

This behaves the same as in numpy:
- For dense tensors it is the product of the shape elements.
- For sparse tensors it is the number of elements actually stored
(including zeros that are explicitly stored).

Fixed some broken tests due to imports

The problem was that get_test_value and missing_test_message are
recognized by nosetests as test functions, and thus test code that does
"import *" from tensor/basic.py could end up trying to run these
functions as tests.

Added the test in reverse order.

added some defensive programming

shape

TST: test CURAND rng when shape is a Variable

Also renamed several arguments to make them less verbose.

This makes the tests pass but nosetests still segfaults.

Added "theano-cache list" to list the content of the theano cache

Minor fixes