Update node with nvm, migrating global modules

nvmi.sh

# Usage: nvmi v6.0.1 (will install specified version)
# Usage: nvmi_latest (will install latest node version)

# these functions will replace the current 'default' version known in the shell.
# to install a node version next to your current 'default' just use nvm install vX.X.X

function nvmi() {
  CURRENT=$(node -v)
  nvm install $1 --reinstall-packages-from=$CURRENT

  nvm alias default $1
  nvm uninstall $CURRENT
}

function nvmi_latest() {
  CURRENT=$(node -v)
  LATEST=$(nvm ls-remote | tail -1 | grep -E -o '.{0,0}v.{0,6}' | tr -d '\n')

  nvm install $LATEST --reinstall-packages-from=$CURRENT

  nvm alias default $LATEST
  nvm uninstall $CURRENT
}