queue: git hooks naturally don't provide topological branch heads

queue: add incoming queue handler

queue: data is a string, we need item (TypeError)

queue: work around parse_command_line() ignoring the first argument

queue: add hook handler (only for bitbucket at the moment)

viewer: use thread-local IOLoop instance (recommended by Tornado docs)

viewer: pass listen address to listen() as a positional argument

requirements: works with Tornado 4.4

viewer: add initial delay to mascots popup animation

utils: adopt now() (renamed to timestamp()) and parse_timestamp(), test them