Improve version

    $>docker version #daemon running
    Client version: 0.5.3-dev
    Go version (client): go1.1.2
    Server version: 0.5.3-dev
    Go version (server): go1.1.2
    Last stable version: 0.5.3

-

    $>docker version #daemon not running
    Client version: 0.5.3-dev
    Go version (client): go1.1.2
    2013/08/19 12:09:37 Can't connect to docker daemon. Is 'docker -d' running on this host?

Fixes #1559