FLUID-5485: Added UIO docs

Converted the following wiki pages to markdown:

http://wiki.fluidproject.org/display/docs/User+Interface+Options+API
http://wiki.fluidproject.org/display/docs/Tutorial+-+User+Interface+Options


http://issues.fluidproject.org/browse/FLUID-5485
The second occurrence of "prefsEditor" could be codified here.