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 as a follow up ... 

I was chatting w @bstopp around NIT and he lamented on how it doesnt work for Adaptive images. One thought for the ad hoc "transformers" (wrong name?) would be an AdaptiveTransformer that pulls values from suffix (like so `/transform-name/<width>/<height>/image.png`) and resizes the image

`adaptive:allow=100x300&allow=200x600` 

It seems like theres potential for a set of logic that can get "complex" (or atleast verbose) that doesnt fall into the pure layer-based image transformers.