hack/PACKAGERS.md: libdevmapper
Factor cache-probing logic out of buildfile.commit() and CmdRun().
Record added-tree sha256 in buildfile.CmdAdd, probe and use cache.
Add testcases for ADD caching, closes #880.
Add self to AUTHORS.
Add CHANGELOG.md entry for ADD caching.
Always copy dockerinit locally, regardless of whether our docker binary is static, because even it might get deleted or moved/renamed
Add dockerinit SHA1 and path to "docker info" when debug mode is enabled
Allow packagers to specify a custom dockerinit lookup location via DOCKER_INITPATH in dynbinary

Only necessary if distro policy dictates that the path deviate from the paths already listed in utils/utils.go - please refrain from using it otherwise.
Handle compressed tars in ApplyLayer

When pulling from a registry we get a compressed tar archive, so
we need to wrap the stream in the right kind of compress reader.

Unfortunately go doesn't have an Xz decompression method, but I
don't think any docker layers use that atm anyway.
Tidy up some of the error messages from apt during build
archive: Re-add XZ compression support

This shells out to the xz binary to support .tar.xz layers, as
there is no compression/xz support in go.
Canonicalize our root path before we try using it, because we make assumptions about it not containing symlinks

Fixes #3242
Fix OSX build for sysinit
Fix OSX compilation for aufs
Add -a to our BUILDFLAGS directly, which fixes some fun test compilation issues

Also, now that we use "-a", we no longer get any benefit from "go test -i", and it actually causes problems sometimes, so let's nuke it.
Merge pull request #3266 from tianon/fix-integration-test-building

Add -a to our BUILDFLAGS directly, which fixes some fun test compilation issues
Merge pull request #3264 from creack/fix_osx_compilation

Fix osx compilation
add some debug to runtime.restore()
Merge pull request #3263 from tianon/abspath-root

Canonicalize our root path before we try using it