installer: Bump bootstrap timeout
installer: Bump bootstrap timeout

Copying images on EC2 can take a few minutes.

Signed-off-by: Jonathan Rudenberg <3692bfa45759a67d83aedf0045f6cb635a966abf@titanous.com>
flynn/flynn,lmars/flynn,lmars/flynn,flynn/flynn,lmars/flynn,philiplb/flynn,philiplb/flynn,flynn/flynn,flynn/flynn,flynn/flynn,philiplb/flynn,lmars/flynn,lmars/flynn,philiplb/flynn,philiplb/flynn