box安装错误
mac系统安装，执行vagrant时报错如下：
/opt/vagrant/embedded/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- vagrant-share/helper/api (LoadError)
from /opt/vagrant/embedded/lib/ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
➜ ~ git:(master) ✗ vagrant -v
Vagrant 1.9.4
➜ ~ git:(master) ✗ VirtualBox --help
Oracle VM VirtualBox Manager 5.1.22
解决方法：
➜ ~ git:(master) ✗ vagrant plugin install vagrant-share --plugin-version 1.1.8
