Use nvm instead of local npm

Easier to use different nodejs versions and have "global" packages
that don't need root to install.

See: https://github.com/creationix/nvm

Signed-off-by: Alan Orth <alan.orth@gmail.com>

.npmrc

@@ -1 +0,0 @@
-prefix=${HOME}/.npm-packages

.zshrc

@@ -69,9 +69,9 @@ export PAGER=less
 # look for Ansible hosts file in current directory
 export ANSIBLE_HOSTS=hosts
 
-# Enable user's "global" npm packages
-if [[ -d ~/.npm-packages/bin ]]; then
-    PATH=$PATH:~/.npm-packages/bin
+# Enable node version manager (nvm)
+if [[ -d ~/.nvm ]]; then
+    . ~/.nvm/nvm.sh
 fi
 
 # Enable pyenv