remove links to obsolete application/vnd.mitre.pdmp+xml docs
use the r2 schemas in the search result atom feed
update tests to use r2 schemas
remove obsolete r1 pdmp views
remove obsolete r1 pdmp mime type
Merge branch 'r2_schema'
add a small margin above alerts to keep them off the navbar
remove message about signing up

We don't allow signups so it's frustrating to tell the users to do it.