Have watchdog listen on stdin for messages.

Stdout appears to always work.
Make sure to shutdown cluster when controller goes away.
add lreg example.
change test_lreg to use code im example.linear_regression
add ndim property for distribute array
add ndim to both Expr and DistArray
init commit for sklearn
finish Linear Regression
now make distarray is always larger than broadcast array
fix linear regression
Fix broadcasting.

The wrong dimensions were being trimmed when fetching from a
broadcast array.  If input matrices happened to be square, then
this would trigger the error.
Make rpc timeouts configurable.