Related it issue #107
Adds custom error pages all pointing to the /notfound page so the defined headers are sent for error pages
Adds Pragma, Expires, X-Content-Type, X-download, X-Content-Security policy, Content-Security-Policy to apache configs
Removes X-XSS-Protection header from apache configs
changed `no-sniff` to `nosniff` thanks @Taipo issue #107
re-added x-xss-protection header
grouped the headers together
fixed caps

fixed caps
copied same comments from source.site to document.site
removed duplicate header
added pacing and comment
Merge pull request #199 from dolanjs/apache-headers-fix

Apache config headers and error page fixes. Closes #107, fixes #192