Rewrite linux/nfs_cleanup for security and multi-user, fixes #7938
Rewrite linux/nfs_cleanup for security and multi-user, fixes #7938

Avoid using a temporary file, rather do the substitution in Ruby and
write /etc/exports directly.

mwrock/vagrant,PatrickLang/vagrant,gitebra/vagrant,marxarelli/vagrant,justincampbell/vagrant,bdwyertech/vagrant,crashlytics/vagrant,bdwyertech/vagrant,crashlytics/vagrant,bshurts/vagrant,benh57/vagrant,chrisroberts/vagrant,chrisroberts/vagrant,taliesins/vagrant,bshurts/vagrant,sni/vagrant,crashlytics/vagrant,jtopper/vagrant,benh57/vagrant,jtopper/vagrant,mitchellh/vagrant,PatrickLang/vagrant,sni/vagrant,bshurts/vagrant,jtopper/vagrant,justincampbell/vagrant,bdwyertech/vagrant,crashlytics/vagrant,chrisroberts/vagrant,mwrock/vagrant,benh57/vagrant,chrisroberts/vagrant,benh57/vagrant,sni/vagrant,mwrock/vagrant,sni/vagrant,PatrickLang/vagrant,gitebra/vagrant,jtopper/vagrant,justincampbell/vagrant,bshurts/vagrant,taliesins/vagrant,mitchellh/vagrant,mitchellh/vagrant,bryson/vagrant,marxarelli/vagrant,marxarelli/vagrant,gitebra/vagrant,bdwyertech/vagrant,justincampbell/vagrant,bryson/vagrant,bryson/vagrant,taliesins/vagrant,taliesins/vagrant,mwrock/vagrant,mitchellh/vagrant,bryson/vagrant,marxarelli/vagrant,gitebra/vagrant,PatrickLang/vagrant