Fix page titles

Internal pages get site.title appended to the end
Fix "Sobre" page title
Add grunt-uncss task

Removes any css that isn't used in the website. Inuitcss is responsible for most of it, as it do not have a "silent" option and we're extending it's classes instead of using they in the HTML.
Add grunt-contrib-cssmin task

Minifies grunt-uncss output
Add grunt-contrib-htmlmin task
Change task names

Also do little changes to browser_sync task
Add last minification tasks to build:prod task