Disable NFS on OS X and Fix issue with initdb

Merged Gabriel Mazetto requested to merge brodock/gitlab-development-kit:disable-nfs-on-osx into master

Syncing GDK folder using rsync instead of vagrant default share, will fix #46 (closed).

Disabling NFS on OS X will make sure we don't have incorrect UID/GID on guest machine, as described on #68 (closed).