add Spawner.debug

for easy debugging of the single-process output
fix env when using setuid

avoids subprocess identifying as root
Merge pull request #47 from minrk/single-user-auth-failure

handle failure to check authorization
mock out user-env

since tests don't use real users
Merge pull request #46 from minrk/setuid-env

fix env when using setuid
add orm.User.find and orm.[Foo]Token.find

for simple get-by-name access
cookie_secret is no longer bytes

add utils.random_hex for generating a unicode object
with random hex bytes
fix inverted logic in Server.is_up()
allow resetting the database
check if spawners are running before starting new ones
enable resuming Hub state from database
update proxy with already-running users at startup
update mocking with load-from-db changes