A datagrid instance should have simple switches to enable different GC with basic defaults and active logging

For DG isntances it is essential to check the GC behaviour in case of problems.
Also there should be a simple switch to select G1 CMS or Shendora, maybe completely switch off to use the environment variable to append it to the parameter manually.

It should enable the GC policy with a single variable like
JVM_DATAGRID_GC=G1||CMS||Shendory||NONE
and calculate the different options based on that and the cgroup resouces
JVM_DATAGRID_GC_LOG=true||false
should set the parameters to have a rotating gc logfile in /opt/datagrid/standalone/log folder