Bower support.

This request for discussion. Not for merge.

I add configuration for bower, but it will be work only if you have  "sp/bower-bundle" in your application. But I have many question for work done.

1. I think support bower(bower-php) is really needed and will be usefull. But  you #19 ?  Do I continue to implement feature?
2. I think code  need to some refactoring. Can i do this?
3. Font. Now i use this assetic config.
````
   assets:
        glyphicons_eot:
            input: "@BraincraftedBootstrapBundle/Resources/public/components/bootstrap/dist/fonts/glyphicons-halflings-regular.eot"
            output: "fonts/glyphicons-halflings-regular.eot"
        glyphicons_svg:
            input: "@BraincraftedBootstrapBundle/Resources/public/components/bootstrap/dist/fonts/glyphicons-halflings-regular.svg"
            output: "fonts/glyphicons-halflings-regular.svg"
        glyphicons_ttf:
            input: "@BraincraftedBootstrapBundle/Resources/public/components/bootstrap/dist/fonts/glyphicons-halflings-regular.ttf"
            output: "fonts/glyphicons-halflings-regular.ttf"
        glyphicons_woff:
            input: "@BraincraftedBootstrapBundle/Resources/public/components/bootstrap/dist/fonts/glyphicons-halflings-regular.woff"
            output: "fonts/glyphicons-halflings-regular.woff"

````

And it dump good. Why do you use comand for this?