Make AsseticBundle works with AssetCache

[scourgen]

I found out that kriswallsmith/assetic supports cache ,but this bundle doesn't work with it. So I made some change to make it works,that's useful for projects which has a lot of js/css files like mine.

[ghost]

Please adapt this PR to the symfony/psr coding standards: http://symfony.com/doc/master/contributing/code/standards.html

[scourgen]

If It still has something wrong,please tell me,thanks .

[kriswallsmith]

Hi @scourgen,

Thanks for the pull request. At first glance this change adds a layer of complexity that doesn't appear to be worth it. Why do you think this should be added?

Thanks, Kris

[scourgen]

I have a project that has hundreds of js/css files, on each times of deploy, We need spend about 10 minutes to compile all js/css fies(I was use google compiler for js and yahoo compiler for css). Since we deploying frequently, We waste a lot of time on deployment. So I want find a way to make it faster.

So basically What I do is adapt the dump command with AssetCache. the purpose of that is make assets cacheable(If the source code doesn't change,then just use the exist complied version instead of compile it again.)