recreate build status badge for shippable

i deleted the project at shippable and recreated
while troubleshooting errors in the shippable web hook.

github shows that shippable is returning an "invalid response 404"
even though i can see the config in shippable web gui plus trigger
manual builds against master branch.

i'm going to leave the badge and service hook in place for now;
maybe it's a transient problem on shippable's end.