[MIR] plainbox-provider-checkbox

Following https://wiki.ubuntu.com/MainInclusionProcess and
https://wiki.ubuntu.com/UbuntuMainInclusionRequirements

I have checked the following requirements:

Availability: the package is available in Debian and Ubuntu 14.04

Rationale: The package is a new (upcoming) dependency for a package already
in main, checkbox. As of 14.04, checkbox jobs and scripts won't be shipped
by checkbox but by individual "provider" packages. This package provides
all the jobs/scripts/data/whitelist files formerly included in checkbox.

Security: this is not an entirely new package because it provides the same
jobs and scripts that checkbox provided, with no known security issues. A
team of people supports the package so any discovered issues can be
addressed quickly.

Quality assurance: the package is a dependency for checkbox so it's not
aimed at end users directly. The package is maintained in Debian and Ubuntu
and has no outstanding bugs reported there. There are many bugs reported on
the upstream project itself but those are used for tracking development
internally by the team. The package is used daily without major issues (from
a development PPA). The package uses debian/watch file to track new releases.

UI standards: NA

Dependencies: All in main

Standards compliance: The package is standards compliant.
Note: It overrides the following lintian tag:
http://lintian.debian.org/tags/image-file-in-usr-lib.html
With plainbox 0.6 (planned next month), provider packages will install all
read-only architecture independent data files in /usr/share.

Maintenance: The package is maintained by the hardware certification team
inside Canonical. It is a relatively simple set of python modules so that
should be more than sufficient. There is no Ubuntu/Debian delta now nor can
the reporter imagine a reason why that should ever change.

Background information: the package description contains extensive
description of the purpose and scope of the package. This package was not
renamed recently, or at all.