feat(fleetctl): add a version

The version pkg will have the version number shared by fleet and
fleetctl.
feat(fleet): add a version flag
fix(fleet): use config not config_file

Follow etcd and call it simply config not config_file.
Merge pull request #115 from philips/add-release-version

Add a release version and fix config_file
feat(machine): Poll for machine state on each heartbeat

* Refactor Machine into Machine with static/dynamic MachineStates
* Refresh dynamic MachineState before pushing state to Registry
* Replace references to machine name with bootid
refactor(AgentState): Rename GetUnbadeOffers -> GetOffersWithoutBids
refactor(AgentState): Drop unused method GetBadeOffers
fix(fleetctl): Only set default --tunnel port if value provided
fix(systemd): panic when unable to connect to dbus