website/docs: update getting started guide to use box directory
core: box URLs can be authenticated by hooking
core: box checksums just work properly again for direct box adds
core: BoxMetadata supports checksums
core: checksums supported when adding box from metadata
website/docs: update docs for checksums on versioned boxes
core: duplicate URL array when authing so we don't mess up original
Read box file in binary mode for checksum
Merge pull request #3045 from bmorg/master

core: read box file in binary mode for checksum
Update CHANGELOG
Set param -name automatically (docker run)

``-name`` ist needed for linking containers, i.e. see http://docs.docker.io/en/latest/use/working_with_links_names/#working-with-links-names
added as ``args << ``
core: Vagrant.installer_embedded_dir
core: load system plugins if they are installed
core: add tests fornew systems path for plugin manager
core: plugin manager marks system gems as system
commands/plugin: list notes system gems
core: better error if attempting to uninstall system plugin
core: safer dup checks for synced folders
Merge pull request #3051 from mattes/patch-1

provisioners/docker: set param -name automatically (docker run)