add mem-per-cpu to still be able to work with changed taurus config

The taurus default memory limit for GPU jobs has been the maximum memory available (3000MB per core) - till now. 
Due to an update, this has changed to 300MB per core by default, but can be set to 3000MB per core manually.

This pull-request adds this configuration to the `*.tpl`.

Info:
`--mem-per-cpu` actually means *memory per cpu-core* in MB.