add class options to viewer navigation
refs #13 -- treat navigation as subnav and add a pages site nav icon
refs #13 -- get rid of page types index and add subnav
refs #13 -- add setting subnav
we ignore symlinks when middleman is a segment in the path
refs #13 -- add subnav to forms
fixes #16 -- admins are part of every project

fixes #17 -- admins can edit any user

refs #13 -- add user subnav
refs #16 -- don't create a site user when we create a project

because that user has to be an admin in the first place
prepend an underscore when template class starts with number