Err msg et small opt in python code

Don't complain about MKL threading on mac since openmp doesn't work.

Fix problems in release buildbot

Prepare release candidate 1.0.0rc1

Optimize SUM(x^2), SUM(ABS(X)) and MAX(ABS(X)) to cuDNN reduction.

Make sure MKL uses GNU OpenMP.

Fix invalid casts and index overflows in signal.Pool

Change some texts to prepare theano 1.0.

Refactor dnn conv functions

(ws/stride/pad may be int32 or int64; int32*->int64* is a strict
aliasing violation, int64->int32 is a possible overflow)
https://bugs.debian.org/878596

Cite the papers about MRG31k3p in the code. Not just in the acknowled…