Merge lp://staging/~ralsina/ubuntu-push/server-limits-doc into lp://staging/ubuntu-push

PACKAGE_DEPS (+1/-0)
client/service/service.go (+2/-0)
client/service/service_test.go (+17/-0)
client/session/session.go (+3/-3)
debian/config.json (+1/-1)
docs/_common.txt (+43/-0)
docs/example-client/main.qml (+34/-17)
docs/example-client/manifest.json (+1/-1)
docs/lowlevel.txt (+2/-0)
launch_helper/kindpool.go (+3/-2)
launch_helper/legacy/legacy.go (+3/-4)
server/acceptance/suites/helpers.go (+7/-6)
server/api/handlers.go (+12/-0)
server/api/handlers_test.go (+6/-6)
server/broker/testsuite/suite.go (+11/-11)