Improve the link command in _brew.
Fix vagrant vm name matching:

- escaping of single quotes
- match older vagrant files which uses keywords as vm names.
Merge pull request #195 from babysnakes/fix-vagrant-completions

Fix vagrant vm name matching
Merge pull request #193 from xuhdev/improve-brew-link

Improve the link command in _brew.
added simple completion for exportfs
Merge pull request #198 from TimofeyTitovets/master

added simple completion for exportfs