Remote control of spool; support downing specific ports; spool expiration

[EvanKrall]

This branch adds 3 primary features:

• The ability to down specific ports of a service.
• Optionally (gated by a config flag), POSTs to /spool/<service>/<port>/<query> will up or down a service remotely.
• Spool files can have an expiration date; if hacheck reads the file after its expiration, we delete it. We also keep track of creation time.

This branch also includes my changes from #23 so I could run tests.

[EvanKrall]

Rebased on top of my new version of #23 to get py26 tox support; fixed my py26 issues. Hopefully travis will be green now.

[EvanKrall]

@solarkennedy @jolynch @jnb Any of you want to take a look at this?

[jnb]

Nit, to avoid issues with falsey values:

if extra_info.get('creation') is not None:
    ...

[jnb]

Worth commenting why you first check with port=None?

[jnb]

lgtm

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