Named Image Transformer - Image Quality Transformer

All Image Quality to be specified per Named Transform

quality values range from: 0 - 100 [ low - original layer quality ]

Transform params are in the format: `quality:quality=50`

Moved the quality computation to usual, final layer.write(...) call.
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![image_jpg__1170x780_](https://cloud.githubusercontent.com/assets/1451868/4946810/9c9d0d3a-6619-11e4-8cef-7d95e30bd117.png)

![image_jpg__1170x780__and_namedtransformimageservlet_java_-__acs-aem-commons-bundle__-_acs-aem-commons_-____dropbox_code_acs_acs-aem-commons_](https://cloud.githubusercontent.com/assets/1451868/4946830/d8d7f1b6-6619-11e4-8c30-6124154711cb.png)

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Updated approach to #347 and #348
Just to avoid cluttering the NamedImageTransformerImpl; Conceptually it functions similarly to the other transformers in that it does a specific job in effecting the rendering of the Image. Currently `NamedImageTransformerImpl` does "general work" and not more pointed jobs like this.

I'm not opposed to C/Ping up if there are strong feelings about it