Reported by: @lattera
Reviewed by: @AdSchellevis

(os-update was renamed to opnsense-update.)

(spam, spam, spam, spam...)

Submitted by: @fabianfrz, @DokuKaefer

Also adds a custom user agent to make it easier to filter by version
and moves the crash reporter to a more visible location in the system
category.  :)

(legacy) crashreport PHP Warning:  in_array() expects parameter 2 to be array, null given in /usr/local/www/services_dhcpv6_relay.php on line 162

(legacy) fix crashreport PHP Warning:  substr_count(): Empty substring in /usr/local/www/services_ntpd.php on line 290

Spotted by: @fabianfrz

Work on replace remaining legacy theme instances #303