Adding watch for .nvmrc

In the event that .nvmrc is found in a directory, change to that version of node using NVM.

plugins/nvm/nvm.plugin.zsh

@@ -3,3 +3,15 @@
 
 # Load nvm if it exists
 [[ -f "$NVM_DIR/nvm.sh" ]] && source "$NVM_DIR/nvm.sh"
+
+# Look for .nvmrc in directories.  If found, change to that version of node.
+autoload -Uz add-zsh-hook
+load-nvmrc() {
+  if [[ -f .nvmrc && -r .nvmrc ]]; then
+    nvm use --delete-prefix
+  elif [[ -f package.json && -r package.json ]]; then
+    nvm use --delete-prefix v6.11.1
+  fi
+}
+add-zsh-hook chpwd load-nvmrc
+load-nvmrc