Optimize fonts

[xferra]

1. Cleanup and restructure all font properties in CSS, for example using CSS variables;
2. Install npm package font-awesome with the same version as now on CDN (or use latest from CDN);
3. Minify font-awesome using fontmin and gulp - so, only required icons ans styles should be included for deployment;
4. Find a proper way to load Gooogle Fonts: FAQ, Google Fonts API, Fonts Blog, webfontloader - they are connected in the header;

PS: 3* - as an idea - leave a link to CDN and then during gulp default - execute a new task that will replace it with the locally optimized variant.
PS2: Analyzing Web Font Performance

All ideas and remarks are welcome.
Part of generic Optimization issue #39