Move install code to a separate module

* Move the install stack to the file installStack.js. This new module
  specifies the "install/commit" route.
* app_install now references the installStack module
* Add utility scripts uninstall.sh and create_db.sql
* Update install.sh to call "node app" instead of "node app.js" This is a
  neat shortcut I learned, and I'm implementing it here in hopes to share
  it with other developers.