Fix crontrigger not firing on day of week.

It turns out that jqcron, the script I use for easy configuration of
cron values, is off by 1 in the day of week field. Easy fix to just add
it back.
Convert Date datatype to Timestamp, setLeader fix

Apparently, the Date datatype only has resolution to 1 day and I need
resolution to 1 second. So had to change it to Timestamp.

Also added stack trace printing to exceptions, so they don't fail
silently.

Also changed setLeader in HostsTable to update the entry instead of
deleting and then recreating it. Deleting and recreating the entry
resulted in data loss as the prior run records was also deleted.
Add save indicators to system config UI.

Previously there was no indication whether clicking the save
configuration button actually did anything. Added some callbacks so that
the user would have an visual indication that something is happening.

The user will know when a save is in progress and when a save has
succeeded or failed. This save message will also remove itself after a
few seconds.