Revert "Adds documentation on new changes brought up by vagrant-rekey-ssh"

This reverts commit 237874df18091e335a24b0c44466f15c605df98d.
Revert "Makes installation of vagrant-rekey-ssh plugin mandatory"

This reverts commit d74a69db2a3349637f52b1c0beb58995fd07ca74.
Revert "Adds help text for connecting to databases via SSH tunnel"

This reverts commit 3d8b6153f729f8b429d9ebf7e4817c7dec1d4993.