setup.py: replaced calls to open() with codecs.open() to read non-ASCII characters...

... when building LONG_DESCRIPTION string from the contents of NEWS.txt, DESCRIPTION.txt.  It helps fix an exception being thrown when building from master in python 3.3.4.  See [this](https://groups.google.com/forum/#!topic/theano-users/a0obHkVaRmo) thread in theano-users for details.