Run `npm build .` after cached install

Before this change, `node_modules/.bin` was not populated when a module
was installed from the cache.

This change add a call of `npm build .` to let npm execute all necessary
post-install steps.

A side-effect of this change is that `preinstall`, `install` and
`postinstall` scripts are executed too.
Merge pull request #4 from strongloop/feature/node-modules-bin-links

Run `npm build .` after cached install