Refine vagrant nfs mount options to avoid locking issues

Since a while I've been facing problem with the nfs mount options - gradle used to abort due to failure of locking some cache files. *(I'm not sure when I faced the locking issue for first time: it's either due to updates in my Ubuntu or due to vagrant updates).*

I managed to workaround the problem by either by:
* mounting the nfs with `ver=4` (instead of `ver=3`)
* or by adding `nolock` option

The `no*atime` changes are just general performance suggestions (not related to fixing errors).

The changes in this PR work fine for me with current version of vagrant (`1.4.1`) on Ubuntu 13.10 64-bit.