better redialing - #7

For supposed efficiency sake I was redialing non-active connections in
their own background goroutines, which wasn't behaving as expected.  A
net split with all the database nodes ended up throwing the main process
into a 100% cpu eating loop calling session#Available over and over.  This
no longer occurs and sessions are properly redialed now.

Also removed the completely useless state parameter inside sessions,
which was another reason sessions weren't redialing correctly.