- Partially removed a confusing mention of THEANO_FLAGS which was a leftover
  from a previous version where it was shown in the suggested nosetests command
- Removed mention of warn.ignore_bug_before since tests are now automatically
  configured to avoid printing those warnings

This is needed e.g. for the --with-id option of nosetests to work properly.

merge w conflicts in cuda init and nvcc_compiler - I had to clobber my previous commits which were bad

This is useful e.g. to be able to copy a precompiled cutils_ext into the
compiledir *after* reading the value of theano.config.compiledir.

- Fixed crashes in an unusual Python 2.4.4 Windows environment when calling
  subprocess.Popen with a mix of PIPE and None values for stdout, stderr and
  stdin.

- Fixed crashes when using a C cache copied from another location.

However, this warning will not be emitted if deleting all modules (this is
done by "theano-cache clear", for instance).

Partly reverts 5ff6e487f285.

Revert f46a8b820217, 90b692809391 and 6d8724480dab.

That was printed directly to stdout, regardless of the redirection set
by nosetests. I have no idea how print in C to Python's sys.stdout.

This should avoid flooding the buildbot's output.