add functionality

ts/npmci.install.ts

@@ -1,3 +1,22 @@
+import "typings-global";
+import * as plugins from "./npmci.plugins";
 export let install = (versionArg) => {
-    if(versionArg = )
+    let done = plugins.q.defer();
+    let version:string;
+    if(versionArg = "lts"){
+        version = "4";
+    } else {
+        version = versionArg;
+    };
+    plugins.beautylog.log("now installing " + "node ".green + ("version " + version).yellow);
+    plugins.shelljs.exec(
+        "bash -c \"source /usr/local/nvm/nvm.sh && nvm install "+
+        version +
+        " nvm alias default " +
+        version +
+        "\""
+    );
+    plugins.beautylog.success("Node version " + version + " successfully installed!");
+    done.resolve();
+    return done.promise;
 }