Add option to Docker provisioner to build local images
Remove defunct @build_options reference
hosts/bsd: don't execute shell for sudo commands [GH-2808]
hosts/bsd: use Util::Which instead of system("which")
synced_folders/rsync: move rsync logic out to helper
synced_folders/rsync: `vagrant rsync` syncs the folders
synced_folders/rsync: expand host paths relative to root path
core: MixinSyncedFolders#synced_folders does scoped hash override
synced_folders/rsync: pass --delete option to delete bad files
website/docs: document `vagrant rsync`
Merge pull request #2816 from mitchellh/f-rsync-command

"vagrant rsync" non-primary command
add listen as a dep
core: interrupt in Cli exits with 1
synced_folders/rsync: rsync-auto command
synced_folders/rsync: unit tests for the callback, fix bug
website/docs: rsync-auto
website/docs: better docs
Merge pull request #2820 from mitchellh/f-rsync-listen

`rsync-auto` command
Merge branch 'add_building_local_dockerfiles' of https://github.com/jpfuentes2/vagrant into jpfuentes2-add_building_local_dockerfiles
provisioners/docker: unit tests for config

/cc @fgrehm - I'm starting to unit test more and more of the plugins.
Just showing you an example because it is quite easy. :)