Adding more tests around `auth.ResolveAuthConfig`

mostly because I've been failing at getting docker `0.6.2` working with
docker-registry `0.6.0` with regard to login and push.  I suspect there
may be some mismatched expectations between `auth.ResolveAuthConfig` and
`registry.ResolveRepositoryName`, but I haven't done enough research or
experimentation to think it's anything more than user error.  More tests
are good, no?
Configured FPM to make /etc/init/docker.conf a config file.
Hint for Remote API doc details in header links
Used tabs for alignment when I should've used spaces. Fixed.
Clearly point at detailed docs
Fix Ping endpoint documentation
Add/modified the canonical link to work with all /index/ links. Added style for "danger'
Cleanup
fix(hack/PACKAGERS): add xz utils as a runtime dep
Update ubuntu docs to use wget instead of curl

Ubuntu doesn't come with curl.

wget instead of curl

nicer wget syntax

remove /dev/null
Merge pull request #2065 from kyleconroy/fix_ping_endpoint

Fix Ping endpoint documentation
Merge pull request #2073 from tianon/gentoo-no-more-1422-hack

Remove Gentoo install notes about #1422 workaround
Merge pull request #2063 from dhrp/doc-template-fix

Doc template fix
Merge pull request #2060 from mastahyeti/patch-1

Add `apt-get install curl` to Ubuntu docs
Merge pull request #2069 from philips/add-xz-to-runtime-dependencies

fix(hack/PACKAGERS): add xz utils as a runtime dep
Merge pull request #2015 from dsissitka/1927

Configured FPM to make /etc/init/docker.conf a config file.
Merge branch 'hint-api-details' of git://github.com/cdunklau/docker into 2017-api-details

Conflicts:
	docs/sources/api/docker_remote_api.rst
Fix #2017 Merge branch '2017-api-details'
Merge pull request #1990 from modcloth-labs/more-tests-for-auth-registry-resolution

Adding more tests around `auth.ResolveAuthConfig`
keep -r, but default true