Use the async gpu kernel call by default.

make is clear that the allocated space is not needed.

This could speed up thing.

add function to give variables unique names

Minor stuff

It was setting the root logger level to DEBUG.
Also, I do not think the level of the scan logger should be DEBUG
anyway, it should be WARNING by default.

Our transfer call are synchronized version. So no problem there. The
problem that we need to work around is that the Theano gc could free
the output var before we finish with it. cudaFree is instananeous, it
don't get in the stream of command to execute.

Documentation improvements

Consistent & correct handling of integers and gradients

-Documentation and implementation of a consistent way of handling gradients and integers
-Type checks that ensure the gradient is always floating point and not an integer
-Type checks that ensure the gradient of an integer is always undefined or 0
-An upgraded version of connection_pattern that provides theano with enough information to answer questions like "is variable x a function of variable y?" accurately