Separated apps into individual projects

- separated each portfolio app into their own project/github repo
- deleted all respective code/files of those apps
- this repo only contains files relevant to my personal website
Re-added portfolio.js

accidentally deleted portfolio.js
Updated layout

- changed layout template
- changed background colour
- changed portfolio
  - each project has their own page describing the project, linking to
the web application, and linking to the github repo
- added a header image
- added 'active' class, to indicate which page you are on