Update 1-install-and-setup.md (angular#256)

fix missing firebase dependency

Author: sunghyuk

docs/1-install-and-setup.md

@@ -23,7 +23,7 @@ The Angular CLI's `new` command will set up the latest Angular build in a new pr
 ### 2. Install AngularFire 2 and Firebase
 
 ```bash
-npm install angularfire2 --save
+npm install angularfire2 firebase --save
 ```
 
 Now that you have a new project setup, install AngularFire 2 and Firebase from npm.