Apply new design to files page

CHANGELOG

app/assets/javascripts/line_highlighter.js.coffee

app/assets/stylesheets/framework/tables.scss

app/assets/stylesheets/framework/tw_bootstrap_variables.scss

app/assets/stylesheets/framework/variables.scss

app/assets/stylesheets/pages/tree.scss

app/views/projects/blob/_blob.html.haml

app/views/projects/repositories/_download_archive.html.haml

app/views/projects/tree/_readme.html.haml

app/views/projects/tree/_tree.html.haml

spec/javascripts/fixtures/line_highlighter.html.haml

spec/javascripts/line_highlighter_spec.js.coffee