new template: oscar

I have implemented a new template, named "oscar" from ground up.

@canarduck has implemented a [similar theme](https://github.com/canarduck/searx/tree/bootstrax-theme). I have used it a time, and reimplemented good ideas from it in this template.

The template is using [bootstrap](http://getbootstrap.com/) for styling, and typeahead for autocompletion. I have copied all .less-files of bootstrap into the template directory, and build the boostrap.min.css from it. Advantage of that is that we can implement various themes from http://bootswatch.com, including searx specific changes without problems. (is a future idea)

Please update transifex, because many new strings appear in that template