Simplify docker version sed expression (close #282)
Merge pull request #292 from errordeveloper/fix_282

Simplify docker version sed expression

Fixes #282.
cosmetic
don't swallow error
Since sometimes the error is different from what we expect.
git rid of heartbeater goroutine
...by moving the logic into the connection actor goroutine.

The heartbeater goroutine was doing a lot more than just heartbeating;
namely it also had tickers for triggering a ProtocolFetchAll and
initiating a fragmentation test. Furhermore, ensureHeartbeats also
spawned the forwarders.

So this was quite a mix of functionality, and, furthermore, most of it
related quite closely to the connection actor. So moving the
functionality into that simplifies the code.

In the process we also fix #294.
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
fmt
Skeleton of a release script
Add version reporting to weaver
Up to the point of making a git release

(under my own account for the minute)
Better (working) way of checking for a release
Push tagged images to docker
prepare -> build to better avoid mistakes
Put versions in the script and weavedns too, and report them

    sudo weave version
Switch to proper github and dockerhub repo
Don't hardwire executable names; use logical names instead

We could use `os.Args[0]` instead of hardwired names, but that ends up
being e.g. `/home/weave/weaver`. So, use logical names instead.
Quote all echoings and be consistent about the message prefix
Do better with checking the changelog

Before, this could fail without a message if there was a changelog but
no matching line.

Also change the changelog format
      == Release v0.0.1
to
      == Release 0.0.1