Tasks collect log messages, renamed log() to doLog()
jasmine-node captures exceptions

without the --, the argument gets ignored
fixed log test in shellTaskSpec

log event's messages do no longer contain trailing newlines
Task constructor accepts single callback argument
workdir directory of tests is preserved

The workdir is cleared at the beginning if a test suite, and then all
content is preserved for future inspection.
Implemented PersistentTaskContext which saves past tasks
Archive path of PersistentTaskContext can be set lazily
PersistentTaskContext creates log path if not existing
Site and SiteManager are PersistentTaskContexts
fixed task:log event
Showing tasks of sites
Showing more info on site overview