docker service_watcher
default port for docker http
update for docker 0.6.5 port string
argument nil check
spawn thread in constructor
initialize last_containers to empty list

Only call `containers` in `begin`/`rescue` block
bump version to v0.7.0
docker watcher: continue polling if a single host fails
docker watcher: follow log convention
Added JRuby support.
introduce .mailmap

Dedups git shortlog -sne
make the example config file valid json
don't use require relative in the example watcher
minor whitespace cleanup; remove require_relative
ignore jar file artifact
basic infrastructure for allowing watchers to stop cleanly

this is sufficient for the docker and dns watchers, which run in their
own loops
special stop handler for the zookeeper watcher

calling stop! should unsubscribe from pending events, but we handle this
manually anyway
ensure we explicitly stop all watchers in main thread
re-raise exceptions instead of `throw`ing 'em
bump version to v0.8.0