cluster status page

[bacongobbler]

the cluster status view should provide information about Hippo's overall health. Things like:

• status of all Hippo services (bindle, postgres, mail server)
• status of the Job Scheduler (is it healthy? how long has it been running? what is its current capacity levels?)
• status of last backups (did they succeed? When was the last backup? When is the next one scheduled?)
• cluster-wide available resources (#298)
• status of all apps (compressed version of #16 - how many running? How many are stopped?)