Added more templates

* Added checkout, shopping cart, product page
* Made neessory style changes in style.css
Merge pull request #1 from rahulsukla/feature/task-2887

Feature/task 2887
Fix nereid webshop template

* fixed few templates and added scripts to app.js
Merge pull request #2 from rahulsukla/feature/task-3313

Fix nereid webshop template
Add catalog and cart as dependencies
Move the contents out of the web folder
Add templates and static to package data
Patch to add category page #3315

* this patch adds category page in templates
folder and adds macro to render product list in
_helpers.jinja  template.
Merge pull request #3 from rahulsukla/feature/task-3315

Patch to add category page #3315
Send templates and statis to site packages

* templates can now be inherited
* static file handler for webshop separately
Changed the static path of all templates