[1.0][Configuration] Cleanup bundle configuration.

[makasim]

This PR address #287 RFC and partly #294 RFC.

Currently I added a factory only for web path resolver. This is how you can configure it:

liip_imagine:
    resolvers:
       # default options
       web_path:
           web_path: ~ 

       # with custom options
       images_web_path:
           web_path:
               web_root: foo
               cache_prefix: images/cache

Later you can refer to them as before:

liip_imagine:
      filter_sets:
        thumbnail:
            cache: web_path
            filters:
                thumbnail: { size: [223, 223], mode: inset }

        images_thumbnail:
            cache: images_web_path
            filters:
                thumbnail: { size: [223, 223], mode: inset }

[makasim]

added factory for aws_s3 with ability to enable caching.

liip_imagine:
    resolvers:
       aws_s3:
          aws_s3:
              client_config:
                  key:    %amazon.s3_key%
                  secret: %amazon.s3_secret%
                  region: %amazon.s3_region%
              bucket:     %amazon.s3_cache_bucket%
              cache:      liip_doctrine_cache.ns.imagine_cache

[makasim]

just added stream data loader factory

liip_imagine:
    loaders:
        stream_image:
            stream:
                wrapper: gaufrette://image/

[makasim]

@havvg wdyt?

[makasim]

@havvg added tests. Almost done here. Still have to add some tests and update the doc. Other factories will be added in separate PRs.

[makasim]

@havvg ping

[makasim]

added docs. I am going to merge this tomorrow.