fix(builder): bump timeout to 30m

The builer component times out not infrequently because it pulls
deis/slugrunner and deis/slugbuilder. Sometimes, if the Docker Hub
is slow, it takes several tries to get this running. Bumping the
timeout isn't a solution, but it is hopefully a stopgap.
Merge pull request #1524 from deis/bump_builder_timeout

fix(builder): bump timeout to 30m