nodelay is the default, according to the docs
kill stale connections
The weave protocol already effectively performs heartbeating -
FetchAll is performed at regular intervals. Hence we can detect stale
connections by the lack of receiving any data for approximately that
interval (we use x2).

We use the same interval to set a time limit on the handshake too, and
any subsequent interactions prior to the connection being fully
established.

Fixes #272.
Merge branch 'master' into eliminate_heartbeater

Conflicts:
	router/connection.go