serve artifacts on the address that the user tells us to
do not hold the scheduling lock forever if there are no matching offers
avoid consuming resources more than once per task
add support for unspecified HostPort, log tasks that fail to launch
Merge branch 'master' into multinode_support
ran gofmt
Merge pull request #32 from mesosphere/multinode_support

Multinode support; some lingering problems around deleting pods, but those don't seem related to this PR.