fixing embedding dragdiv.mousewheel in viewer
introducing js and css compression using django-pipeline, see #11519

This is first step to make embedding the viewer simple
example of static HTML code in webtest/embedded.html
adding django-pipeline minify to the main build, close #11519

it still requires compressor installation. default is yuicompressor
fixing omeroweb build.xml
removing unused pipeline config from settings.py
upgrading django-pipeline to 1.3.20
fixing image paths in css files and cleaning up jquery-ui