Updating subject and sender for error emails.
Replacing hardcoded install script message with label.
Showing buttons only at the bottom of the err notif settings page. Otherwise buttons don't behave correctly.
Minor text changes to NPSP Resources page.
Merge pull request #698 from SalesforceFoundation/feature/694-error-notif-broke

Feature/694 error notif broke
Merge dev into feature/678-healthcheck-prod-error