Removed tasksel for lamp-server metapackage

[EvanK]

Re-provisioning of an existing server was failing on the tasksel install of the lamp-server metapackage (despite apt having an up to date cache):

 ** [out :: staging.example.com] TASK: [common | Install LAMP stack] *******************************************
 ** [out :: staging.example.com] failed: [127.0.0.1] => {"changed": true, "cmd": "DEBIAN_FRONTEND=noninteractive tasksel install lamp-server ", "delta": "0:00:02.809871", "end": "2015-04-21 10:12:12.324792", "item": "", "rc": 1, "start": "2015-04-21 10:12:09.514921"}
 ** [out :: staging.example.com] stderr: tasksel: aptitude failed (100)

Easiest solution for the time being is to bypass tasksel altogether, and just install the necessary packages with apt.