Add support for the new quality options

[patrickli]

This adds support for the following new quality options:

• jpeg_quality
• png_compression_level
• png_compression_filter

[lsmith77]

needs a rebase .. also tests would be good.

[makasim]

We really need this feature but I am not sure about the implementation.

[patrickli]

Rebased. However I am not sure if unit test is any helpful since these options are just passed own to imagine.

[makasim]

hm, the PR looks unfinished. there is not any tests and you just defined properties but do not use them anywhere

[lsmith77]

@makasim this PR just adds options for Imagine, so they are passed along with the other options.

@patrickli in terms of tests you just need to ensure that they are properly set /~https://github.com/liip/LiipImagineBundle/tree/master/Tests/DependencyInjection

[makasim]

@lsmith77 thanks for the explanation

[patrickli]

Unit test added.

[makasim]

@patrickli thanks