Usersettings: Add variable to disable vim plugings

Some systems just don't need them, but they take quite some time to
install and take up space.

defaults/main.yml

@@ -15,6 +15,9 @@ usersetup_gitconfig: true
 # enable virtualenvwrapper plugin in oh-my-zsh
 usersetup_virtualenvwrapper: false
 
+# install VIM plugins
+usersetup_vimplugins: true
+
 # install VS Code and selectively activate different programming languages
 user_vscode: false
 user_lang_cpp: false