Apache2 no longer working in Yosemite
Okay I solved my problem. It seems like the upgrade of apache had disabled mod_ssl. To debug apache2 config files in osx, run apachectl without any parameters:

Jeroens-MBP: jeroen$ sudo apachectl
AH00526: Syntax error on line 10 of /private/etc/apache2/other/mobilize.conf:
Invalid command 'SSLProxyEngine', perhaps misspelled or defined by a module not included in the server configuration