Npm install error in Vagrant - Fix

This fixes this error:

==> default: npm
==> default:  http GET https://registry.npmjs.org/npm/1.4.25
==> default: npm 
==> default: http 
==> default: 200 https://registry.npmjs.org/npm/1.4.25
==> default: npm
==> default:  http GET https://registry.npmjs.org/npm/-/npm-1.4.25.tgz
==> default: npm
==> default:  http
==> default:  200 https://registry.npmjs.org/npm/-/npm-1.4.25.tgz
==> default: npm ERR!
==> default:  
==> default: error rolling back Error: Refusing to delete: /usr/local/bin/npm not in /usr/local/lib/node_modules/npm
==> default: npm ERR!
==> default:  error rolling back     at clobberFail (/usr/local/nvm/v0.8.26/lib/node_modules/npm/lib/utils/gently-rm.js:41:12)
==> default: npm ERR! error rolling back     at next (/usr/local/nvm/v0.8.26/lib/node_modules/npm/lib/utils/gently-rm.js:27:14)
==> default: npm ERR! error rolling back
==> default:      at /usr/local/nvm/v0.8.26/lib/node_modules/npm/lib/utils/gently-rm.js:36:12
==> default: npm ERR! error rolling back     at Object.oncomplete (fs.js:297:15)
==> default: npm ERR! error rolling back  npm@1.4.25 { [Error: Refusing to delete: /usr/local/bin/npm not in /usr/local/lib/node_modules/npm] code: 'EEXIST', path: '/usr/local/bin/npm' }
==> default: npm 
==> default: ERR! Refusing to delete: /usr/local/bin/npm not in /usr/local/lib/node_modules/npm
==> default: File exists: /usr/local/bin/npm
==> default: Move it away, and try again. 
==> default: npm ERR! System Linux 3.2.0-23-generic
==> default: npm ERR! command "/usr/local/bin/node" "/usr/local/bin/npm" "install" "-g" "npm@1.4.25"
==> default: npm ERR! cwd /home/vagrant/dev/xtuple
==> default: npm ERR! node -v v0.8.26
==> default: npm 
==> default: ERR! npm -v 1.2.30
==> default: npm ERR! path /usr/local/bin/npm
==> default: npm ERR! code EEXIST
==> default: npm
==> default:  ERR!
==> default:  
==> default: npm ERR! Additional logging details can be found in:
==> default: npm ERR!     /home/vagrant/dev/xtuple/npm-debug.log
==> default: npm ERR! not ok
==> default:  code 0