templates: no preview for CMS Collections

* no preview for CMS Primary Datasets, CMS Validated Runs (closes #273)
collections: passing records on collection

* updated collection overview, with record samples passed as arguments
* new layout for “ CMS External Resources” collection page
records: page for "CMS External Resources" records
UI: homepage + entrypages(edu/rsch)

* new “svg” logo
* new home+education+research pages (Laura’s latest design)
* (addresses #218)