Add NetBSD guest support
More specific Solaris <11 detection.

Note: This will probably break on Solaris 12+, but not certain of a better approach for now.
More specific Solaris 11 detection
core: Respect VAGRANT_HOME everywhere

Use `VAGRANT_HOME`env var also for `Plugin::Manager` etc., not only in
the `Environment` class.
Merge pull request #2837 from tmatilai/vagrant_home

core: Respect VAGRANT_HOME everywhere
core: tests for shared_helpers.rb

/cc @tmatilai
core: tests for more shared_helpers
synced_folders/nfs: Register `nfs_client_install` caps to correct distros
providers/virtualbox: retry list hostonlyifs [GH-2831]
Merge pull request #2824 from masteinhauser/patch-1

guests/solaris: More specific Solaris <11 detection.
Update CHANGELOG
core: update translation to help Windows more
synced_folders/nfs: don't nfs_prune on hosts that don't support it
synced_folders/rsync: convert path to cygpath on Windows
core: dont' load rc or profile when getting a cygpath with bash
synced_folders/rsync: make sure host path ends in "/"
core: get tests passing on Windows, more tweaks
Update dep to Bundler 1.5.2
website/docs: clarify rsync i nstallation for Windows
synced_folders/rsync: output directory under watch for rsync-auto