Added base Web App functionalities and models. Minor fixes.

...osetta/base_app/static/icons/mimetypes/audio-x-monkey.png

...e/rosetta/base_app/static/icons/mimetypes/audio-x-mp2.png

.../rosetta/base_app/static/icons/mimetypes/audio-x-mpeg.png

...tta/base_app/static/icons/mimetypes/audio-x-speex+ogg.png

...ta/base_app/static/icons/mimetypes/audio-x-vorbis+ogg.png

...p/code/rosetta/base_app/static/icons/mimetypes/binary.png

...ode/rosetta/base_app/static/icons/mimetypes/contents2.png

...bapp/code/rosetta/base_app/static/icons/mimetypes/deb.png

...code/rosetta/base_app/static/icons/mimetypes/document.png

...pp/code/rosetta/base_app/static/icons/mimetypes/empty.png

...app/code/rosetta/base_app/static/icons/mimetypes/exec.png

...ode/rosetta/base_app/static/icons/mimetypes/extension.png

...de/rosetta/base_app/static/icons/mimetypes/folder_tar.png

...osetta/base_app/static/icons/mimetypes/font-x-generic.png

...app/code/rosetta/base_app/static/icons/mimetypes/font.png

...e/rosetta/base_app/static/icons/mimetypes/font_bitmap.png

...rosetta/base_app/static/icons/mimetypes/font_truetype.png

...de/rosetta/base_app/static/icons/mimetypes/font_type1.png

...a/base_app/static/icons/mimetypes/gnome-fs-executable.png

...etta/base_app/static/icons/mimetypes/gnome-fs-regular.png