Add new Run Now button + fix on callback

[chaadow]

There are times where we don't want to wait for the event to happen and manually execute/run the event.

This PR introduces:

• a new Run now button next to the Enable/Disable button

  • After carefully reading clockwork source code, using event.run(Time.now) handles the setting of event.last
  • it also calls set_last_run to update redis as well.

• Setting Last run in after_run callback

  • I usually have every(1.minutes, 'job_name') { SomeSidekiqJob.perform_async }
  • What can happen here, is that the block can raise an exception. For my case, it can be redis ( the one for Sidekiq not clockwork_web) is down or Out Of Memory for example. But it can also be any ruby error
  • So setting "last_run" on Clockwork_web's redis after being run is a safer and more accurate way to set it than setting it before it's run, which can be misleading

  Here is a screenshot: