Add libapache2-mod-perl2 to Depends

| 18:04:37   Setting up ngcp-panel (1.0.13+0~20130819154931.451+wheezy~1.gbp147ec8) ...
| 18:04:37   ERROR: Module perl does not exist!
| 18:04:37   Enabling module ssl.

 -- https://jenkins.mgm.sipwise.com/view/piuparts/job/ngcp-panel-piuparts/325/console