Add missing pyenv plugin

plugins/pyenv/pyenv.plugin.zsh

@@ -0,0 +1,17 @@
+export PYENV_ROOT=${XDG_DATA_HOME:-$HOME/.local/share}/pyenv
+_init_pyenv() {
+    export PATH="$PATH:$PYENV_ROOT/bin"
+    eval "$(pyenv init -)"
+    if pyenv commands | grep -q 'virtualenv'; then
+	eval "$(pyenv virtualenv-init -)"
+    fi
+}
+if [[ -d $PYENV_ROOT ]]; then
+    _init_pyenv
+else
+    pyenv() {
+	echo -n "pyenv is not installed. Install now? [yn] "; read -q || return
+	git clone https://github.com/pyenv/pyenv.git $PYENV_ROOT
+	_init_pyenv
+    }
+fi