Add ability to pause and unpause queues

[mperham]

Explore adding queue pausing to Faktory, per customer request. Initial thoughts:

• [x] Add toggle button to Web UI /queues page
• [x] Add command API like:
  • [UN]PAUSE default - single
  • [UN]PAUSE critical bulk - varargs
  • [UN]PAUSE * - special syntax for every queue Faktory knows about

Still not sure about the API. Web UI might be enough.

• ADMIN [UN]PAUSE <name> to signify an administrative command?
• QUEUE [UN]PAUSE <name> to group queue administration commands together?

[mperham]

Examples:

QUEUE PAUSE *
QUEUE PAUSE foo bar
QUEUE RESUME *
QUEUE RESUME foo bar

[mperham]

In 1.5.0.