Moved web assets to web/ and implemented a pure PHP compression solution for CSS and JS files

[javiereguiluz]

This fixes #5

[stof]

should be ?jsqueeze to apply the minification only in non-debug mode

[javiereguiluz]

I'm not sure about merging this change. I'd love to hear first the opinions of @weaverryan and @wouterj about it. They both know this topic well and they seem to have strong opinions about it (and definitely more qualified than mine!)

[stof]

@weaverryan ping as there was a typo when mentioning you previously

@wouterj any opinion on this ?

[wouterj]

• I don't like depending on ports, they never are as good as the original ones. If it works with the code in the lib, I'm fine with using it here (although I don't believe we should recommend it).
• Imo, sass/scss files are not public files, they shouldn't be accessed. That's why I vote to put these in app/Resources/public or the like, at least outside of web/. This is also following what the best practices guide says.

[javiereguiluz]

This PR is ready for the final review:

• The assets' sources are moved back to app/Resources/assets/
• The compiled assets are web/css/app.css and web/js/app.js
• The fonts have been moved to web/fonts/ to not duplicate them
• The SCSS is now compiled and the CSS are minified with a PHP library (Leafo\ScssPhp)
• The JS are minified with a PHP library (JsSqueeze)

The result is that:

• The application still looks nice without configuring anything or executing any command.
• If someone uncomments Assetic blocks, everything should still work because we use PHP-only solutions.

[stof]

@javiereguiluz it would be great to provide a way to recompile the assets for contributors (using assetic:dump won't work as the Assetic blocks are commented), and explaining it in the contributing file.

[javiereguiluz]

@stof I think that's a very nice idea! Thanks. I've added a note about contributing in 62417ca

[stof]

@javiereguiluz I suggest putting this in CONTRIBUTING.md instead, to follow the github conventions

[javiereguiluz]

@stof much better indeed. Done in a88b360. Thanks.