[feature/npm-outdated]

- add alias for "npm outdated" to check outdated npm modules

plugins/npm/npm.plugin.zsh

@@ -17,3 +17,6 @@ alias npmD="npm i -D "
 # Execute command from node_modules folder based on current directory
 # i.e npmE gulp
 alias npmE='PATH="$(npm bin)":"$PATH"'
+
+# Check which npm modules are outdated
+alias npmO="npm outdated"