configurable remote batch aggretation
bugfix: variable name
Creating PYTHON_EGG_CACHE directory into $HOME/.python-egg (default) is troublesome
when $HOME is mounted as NFS.
PYTHON_EGG_CACHE is now under /tmp, which is expected to be non-NFS.

connection error from master to worker just after launching shellstreaming command
dramatically dicreases
Signed-off-by: Sho Nakatani <lay.sakura@gmail.com>