Prepare final release 1.0.0

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.