Bootstrap CSS Cleanup/Rewrite to LESS/SASS

Our four page (static) website was initially built around a basic standard Bootstrap theme, but then extended manually. Over the time, our CSS files have become a little cluttered, causing the page to render distorted on some resolutions. Also, we want to clean up the project folder and start using Bower for dependency management. It seems however that the page is still dependent on an older version of Bootstrap. The project consists of three parts: - Migrate the four pages to use the new Bootstrap 3 (either plain Bootstrap 3 or bootstrap-sass) - Remove inline styles in the HTML - Restore the responsive navbar, ensure the elements align properly on all resolutions - Clean up the CSS by utilising LESS or SASS, remove unneeded CSS. - Extend gulp script so it builds the minified sources for the new project structure - Deduplicate header/scripts/footer to a shared PHP include. - Improve Google PageSpeed results, most notably ("Eliminate render-blocking JavaScript and CSS in above-the-fold content", "Optimize images", "Size content to viewport", and "Size tap targets appropriately") - Good score on gtmetrix (most notably deferring the load of the required scripts, if any scripts are required) - Create some favicons - A quick refresh to improve readability, alignment, etc. is very welcome, but a complete redesign is not intended