Add more validations of user input and instructions to cd <app-dir>

/to @bajtos 
/cc @altsang 
/cc @cgole 

The PR includes the following fixes:
- adds a conditional message if the app dir is not `.`.
- adds more validations to user input for names
- fixes the url-not-found warnings on jquery map and favicon for loopback:example

I assume `name` captures the user input to the directory name. I just tested your use case and the patch worked as expected (no cd is printed).