homepage: remove unused JS dependencies and fonts

[mtmail]

Removes 14 files and a bunch of small changes

• removes javascript dependencies for Angular and Underscore, they were not used
• removes old font type of unsupported browsers #iefix. Then turns out the font (copyright Google 2006) isn't even listed on fonts.google.com anymore and the browser default font looks similar enough so removed all font files
• removes solr.svg because is not linked anywhere
• removes the email address. It was already commented out
• best practice to treat even OSM data as text instead of HTML. Leaflet's .bindPopup inserts HTML by default
• best practice to use SRI hashes when loading libraries from CDNs

[lonvia]

Thanks.