Added a resource to view files at a certain commit

This commit also includes advanced styles and the highlight.js
dependencies for code highlighting.
Merge https://github.com/devhub-tud/devhub into view-file

Conflicts:
	src/main/resources/static/css/devhub.css
	src/main/resources/static/less/devhub.less
Merge pull request #30 from JWGmeligMeyling/view-file

Added a resource to view files at a certain commit