Vagrant 2.2.7 发布，增加对 VirtualBox 6.1.x 的支持

vagrant2.2.7发布，本次更新主要添加了对virtualbox6.1.x版本的支持。

Vagrant是一个基于Ruby的工具，用于创建和部署虚拟化开发环境，能帮助开发人员迅速的构建一个开发环境，帮助测试人员构建测试环境。简单地说，Vagrant让我们可以通过代码的方式快速地、可重复地创建针对不同虚拟环境的虚拟机，包括Virtualbox、AWS、Docker等。它使得我们可以一次性地、自动创建多个环境相同的虚拟机，对于软件开发和测试尤其有用。

更新内容：

IMPROVEMENTS:

• guest/opensuse: Check for basename hostname prior to setting hostname [GH-11170]
• host/linux: Check for modinfo in /sbin if it's not on PATH [GH-11178]
• core: Show guest name in hostname error message [GH-11175]
• provisioners/shell: Linux guests now support reboot option [GH-11194]
• darwin/nfs: Put each NFS export on its own line [GH-11216]
• contrib/bash: Add more completion flags to up command [GH-11223]
• provider/virtualbox: Add VirtualBox provider support for version 6.1.x [GH-11250]
• box/outdated: Allow to force check for box updates and ignore cached check [GH-11231]
• guest/alpine: Update apk cache when installing rsync [GH-11220]
• provider/virtualbox: Improve error message when machine folder is inaccessible [GH-11239]
• provisioner/ansible_local: Add pip install method for arch guests [GH-11265]
• communicators/winssh: Use Windows shell for vagrant ssh -c [GH-11258]

BUG FIXES:

• command/snapshot/save: Fix regression that prevented snapshot of all guests in environment [GH-11152]
• core: Update UI to properly retain newlines when adding prefix [GH-11126]
• core: Check if box update is available locally [GH-11188]
• core: Ensure Vagrant::Errors are loaded in file_checksum util [GH-11183]
• cloud/publish: Improve argument handling for missing arguments to command [GH-11184]
• core: Get latest version for current provider during outdated check [GH-11192]
• linux/nfs: avoid adding extra newlines to /etc/exports [GH-11201]
• guest/darwin: Fix VMware synced folders on APFS [GH-11267]
• guest/redhat: Ensure nfs-server is restarted when installing nfs client [GH-11212]
• core: Do not validate checksums if options are empty string [GH-11211]
• provider/docker: Enhance docker build method to match against buildkit output [GH-11205]
• provisioner/ansible_local: Don't prompt for input when installing Ansible on Ubuntu and Debian [GH-11191]
• provisioner/ansible_local: Ensure all guest caps accept all passed in arguments [GH-11265]
• host/windows: Fix regression that prevented port collisions from being detected [GH-11244]
• core/provisioner: Set top level provisioner name if set in a provisioner config [GH-11295]