Support configuration of HTML layout

[nichtich]

Either support configuration of lib/views/base.html or modify it to support at least two more options:

• loading //fonts.googleapis.com/css?family=Open+Sans:700italic,400,700|Droid+Sans+Mono should not be hard coded. I am unsure how to best disable it. Move it into an additional option css with an array of CSS URLs?
• additional option logolink (http://linkeddatafragments.org/).

[nichtich]

Google fonts removed with #71.

[RubenVerborgh]

There is an (undocumented) assetsPath option for this purpose.

[RubenVerborgh]

…but we need a template path too, as this is currently hardcoded.