added some stuff to h2o.py to make rm of tree (sandbox) maybe more robust in windows. hopefully didn't break anything. not clear if it really helps (h2o.py). The issue is well noted on 'net (removing directories with various windows-specific permission or other issues..

GLMScore test prints out a message saying it isn' working till we get the json response for GLMScore updated
Merge branch 'master' of github.com:0xdata/h2o
add some tolerance/retry of errors trying to shutil.rmtree sandbox. worst case, just ignore after retrying once