things to finish on csv-style branch

[evanwill]

get done:

• customized page-gen plugin (with object_template built in)
• implement object_template concept via layouts
• implement THEME ICONS option in theme.yml (if necessary)

do in new branch after merging above:

• figure out issue with 1000s of svg icon sprites?
• media player plyr
• rewrite browse-js
• check through map-js icon use (object_template vs format?)
• check index features icon use (object_template vs format?)
• review Rake tasks to gen derivatives